Justice for Single Mother – Diane Dahn | Bloodline Detectives with Nancy Grace | Forensic Files

[THEME MUSIC] NANCY GRACE: May 1988, Santee, California, a small city just East of San Diego.
Local police get a distressing call. A young mom has been found savagely murdered in her own home.
She did not show up to work, so a co-worker went to her house to find out why she wasn't answering her phone or showing
up to work and discovered that the door was open, and then he discovered Diane in her bedroom.
NANCY GRACE: The victim is Diane Dahn, the mother of a two-year-old little boy Mark.
Police find Mark wandering around the house, his mother's blood is on the toddler's clothes.
There's a certain amount of questions that come along with that, you know. Like, why-- why didn't I die?
NANCY GRACE: The leads come and they go, and then the leads end. But then, 30 years later, a groundbreaking new forensic
tool blows this case wide open. You can take a case that's 30 years old and solve it with what you did.
With all of the new technology, you can't get away with it anymore. This is the story of a horrible murder
of a young mother. Her tot son, who was there when she died, and his 30 year quest to know what happened to my mom.
I'm Nancy Grace. Welcome to "Bloodline Detectives." [THEME MUSIC] NANCY GRACE: Santee, California, May 1988, a small city
in Southern California. It's a pretty small town. It's grown obviously over the years.
Back in the 1980s, it was probably a little sleepier than it is now. It's been built up a lot.
It had a reputation as being, you know, people who are generally very independent
and very different than perhaps the folks who lived on the coast. NANCY GRACE: One of these free-spirited residents
is 29-year-old single mom Diane Dahn. Diane Dahn was a single mom raising her two-year-old son Mark.
They lived in an apartment complex in Santee off Graves Avenue. She worked for the transportation company
here in San Diego. She was a musician. She was a violin player and lots of people
knew her as a really good musician. She was kind of a fun-loving, free-spirited hippie,
I guess is the way she's been described to me, which is interesting. Because then they always say, oh you're a lot like her.
And I think, well, yeah, I guess-- I guess I kind of am like that. These are happy, carefree times for a young, single mom
and her toddler son. Then, on May 2, 1988, Diane doesn't show up for work. Her coworker, Gary Beyer, goes to her home to see if she's OK.
So a coworker went to her house to find out why she wasn't answering her phone or showing up to work and discovered the door was open.
Mark was kind of walking around, not being watched, and then he discovered Diane in her bedroom.
911 OPERATOR (ON PHONE): 911 emergency? GARY BEYER (ON PHONE): A lady laying on the ground.
She's dead. 911 OPERATOR (ON PHONE): OK. Where are you, sir? GARY BEYER (ON PHONE): I'm trying to think of the street.
911 OPERATOR (ON PHONE): OK. Are you on Graves Avenue? GARY BEYER (ON PHONE): Yeah.
911 OPERATOR (ON PHONE): Let me get you the fire department, OK? GARY BEYER (ON PHONE): OK.
911 OPERATOR (ON PHONE): OK. FIREMAN (ON PHONE): Hello. GARY BEYER (ON PHONE): Hello.
This is Gary Beyer. FIREMAN (ON PHONE): What's the problem? GARY BEYER (ON PHONE): There's a dead body in the bedroom.
FIREMAN (ON PHONE): Is that where you live? GARY BEYER (ON PHONE): That's where she lives.
FIREMAN (ON PHONE): Where is she? What's the address? GARY BEYER (ON PHONE): It's on Graves there.
It's an apartment. FIREMAN (ON PHONE): Are you calling from there? GARY BEYER (ON PHONE): Yes.
FIREMAN (ON PHONE): OK. 729. Do you know how she died? GARY BEYER (ON PHONE): No.
I sure don't. They missed her at work, and I came over to see if she was sick, and I just
seen her laying on the ground. FIREMAN (ON PHONE): Gary, we'll be right there. GARY BEYER (ON PHONE): Thank you.
I have no recollection of any of that, but, yeah, I guess, I had blood on me, so I don't know if I was close to the situation.
You know, there's a certain-- there's a certain amount of questions that come along with that, you know.
Like, why-- why didn't I die? We have jurisdiction over that part of the county,
so they would have called us. Then a deputy would have been the initial responder
to examine the scene, you know, kind of figure out what's going on. Given the crime, given that Diane's body was found
in the bedroom, then the homicide unit would have been called to the scene. BRIAN PATTERSON: Sheriff's Department came out,
determined she was deceased. It was quite obvious it was probably a homicide based
on what they saw, so they secured the scene and called the homicide detail. She had sharp force object injuries to her body.
It appeared she had been beaten a little bit or some on the face and head. Imagine the dilemma detectives now face.
Is there a way to coax young Mark to tell them what he has seen without adding to his trauma?
He gave some description as a two-year-old might give, but some description of a man that had been in the apartment.
We don't know if he actually witnessed the attack. I don't believe he gave any indication that he witnessed
something bad happening to his mother, but he definitely gave some information about the man.
When they talked to Mark, he was young obviously, and if I recall correctly, he said a bad man hurt Mommy.
But tot boy Mark cannot recall very much, so police begin to retrace Diane Dahn's last known movements.
They discover that Diane and Mark had dinner the night before with co-worker Gary Beyer,
the friend who discovers her body the next day, and his wife Marilyn. This couple will now play a remarkable role
in this tragic story. The family decided who would be best to raise Mark and the Beyers, the family that she
had dinner with the previous night and friends of the family, ended up raising Mark.
So the Beyers are my adopted family. My mom and dad. They worked together, her and Gary,
and I guess when all this happened, they just felt compelled to take me in, and I never knew the difference.
I was loved. I had a good life. I had all the things that a normal child would have,
you know. I fell on my bike, busted my head, all that stuff. So they were very good to me, and now that I'm older,
I can look back and think how fortunate I was to have that in my life. NANCY GRACE: Fortunately, little Mark is secure with Marilyn
and Gary Beyer. Meanwhile, investigators are struggling. They have a picture of how Diane Dahn is murdered, but no clue
as to who killed her. Any victim of a crime, I imagine there was absolute terror.
We don't know what happened prior to the murder. Was this somebody that she knew?
Knew well? Had just met? A complete stranger? Whatever the situation, whatever the relationship between her
and the suspect, I can't imagine that it would be anything but just terror. The realization that this is taking a very violent turn.
Plus she has a kid. She's in this apartment with a young child that she's caring for.
And by all accounts, talking to family members decades later, loved her son very much.
And I would imagine that's the other thing that goes through your mind. I need to protect my child.
A toddler tells police that a, quote, bad man hurt Mommy. But who is this so-called bad man?
A vicious killer that took his mother's life. That's next on "Bloodline Detectives."
NANCY GRACE: Santee, California, May 1988, police investigating the murder of 29-year-old young mom Diane
Dahn. Her two-year-old son Mark found at the crime scene covered in blood, his mother's blood,
and wandering around the apartment. Little Mark cannot remember very much of what he saw.
Police focus instead on the crime scene. This seemed to be an attack that happened very quickly
and not thought out and planned. That it ended up having, you know, a fair amount of evidence left behind for the investigators
to go through. The detectives arrived, they collected fingerprints inside the apartment.
I believe they collected some clothing that belonged to her, a pillow that was out of place.
There was DNA evidence obtained at the time. DNA really wasn't out there at that time in 1988,
but they did collect fingernail scrapings, hair. NANCY GRACE: Investigators struggled to determine
the motive behind the murder. There was no evidence of sexual assault. She was nude, which you could assume, I guess,
that there is some kind of sexual nature in maybe the attack. But as far as actual evidence, no.
She did have what would we would probably consider defensive wounds based on fingernail scrapings.
There was DNA under her fingernails that were male DNA. Hair that was in her hand.
So it did look like she put up a fight. The original investigators obviously spent a lot of time taking a look at that evidence,
but we're talking 1988, and the use of DNA as part of an investigation was in its infancy.
They did discover that it was not the same hairs that belonged to Diane herself, but they were never able to connect
it to a possible suspect. In 1988, no, I don't think DNA would have been on their minds.
They have foresight to know to collect things and to keep it for possible future analysis.
They would be put into evidence in the Sheriff's property and evidence room, and they
would be stored under that case number in our evidence lockers. Yes, the autopsy was performed and a cause and manner was
homicide by sharp force injury. NANCY GRACE: The crime scene evidence is safely secured
and the results of the autopsy made available. Next up for investigators, a list of potential suspects.
You have no suspect. You have some cases where the suspect might be sitting on the porch waiting for an arrest.
But in this case, there was no obvious suspect. She lived in an apartment complex,
so they would have canvassed the complex for any information regarding people who knew her, people
who potentially dated her, you know, just people who were in her life somehow. The original detectives looked at kind of the usual suspects,
boyfriends, friends, people that she might have known, because it didn't look like there was a forced entry.
So possibly somebody she knew. They would have poked a little bit deeper to see is there somebody there who was angry at her?
A grudge. Had she dated somebody that she broke up with? So we would have had to go on into her private life
as much as possible. This is a very special case, even for veteran detectives. As the investigation stalls and time begins to pass,
police never forget about Diane's son Mark, and they check in on him regularly to see how
he's coping without his mom. But they also hope that somehow he might remember just something from the day
his mother was murdered. I remember sitting down with a psychologist that came and talked to me to see how I was doing,
and the police a couple of times. But throughout the years, I remember them coming over and asking questions and things.
But as the case gets colder, I think it just kind of, you know, they're not going to get any more information,
so it just kind of ended. People have to get on with their lives, and even though this leaves a big hole because a loved one is
killed and they have no answers other than the fact that they were killed, people go on.
And I think it's not that they gave up. I don't know if you ever give up, but there's a certain acceptance after 30
plus years of no answers that this is just the reality that you have to deal with.
NANCY GRACE: As Mark grows up, he struggles for answers to a loss that baffles everyone, including the police.
As the years went by, I think it was probably my early teens when I really started questioning, well,
why did this happen? How did this happen? Who did it? All those kind of questions that would typically
pop up in anything like that. That's when I started thinking to myself, you know, what would life have been
like with somebody that was, from what I'm being told, is just like me? You know, what would it be like to be loved by your own mom?
NANCY GRACE: Mark desperately holds on to anything that physically connects him with his mom.
I started gathering what I could from my grandmother and pictures of her, which I still
have a pretty good collection. I had some notes of hers from marine biology. So living so close to the ocean, I
got really, really into a lot of the creatures that are in the ocean. And then I would go back and I would refer to her notes
and say, OK, look, she had a note in there of this. So there was kind of always an interesting connection.
I think I took a lot of solace in the fact that her body was cremated and thrown into the ocean.
So still to this day, when I go to the beach here in Oregon, even though it's nowhere near San Diego,
I feel connected. I feel close. And it's almost as if you can just feel her presence.
NANCY GRACE: The murderer of a young single mom Diane Dahn remains cold, nearly 20 years.
But then, 2006, the San Diego Sheriff's revisit the case thanks to a brand new DNA technology.
One investigator, Victor Caloca was the investigator in the early 2000s who picked up this case, and this usually
happens with cold cases. This murder happened in 1988, and there would have been a group of detectives who worked on that.
And then, it went cold, and then eventually transfers, retirements, it gets passed on to another detective.
And so Victor was probably in a line of detectives whose fingers touched this case at some point.
Victor put in a lot of work to this case and advanced it as best he could, but again, even in 2006 and 2007,
where he did a lot of work, the DNA had not yet advanced and IGG certainly had not become a part of our investigations
as we know it has in the last few years. Criminologist Cathy Chang then makes a remarkable breakthrough.
She searches through tiny pieces of evidence found in the victim's hand and she identifies
a DNA sample from a hair. She, Chang, believes it may belong to the killer. What I would do first is I would look at the evidence,
and in this case, there was a lot of hairs. And hairs are actually really difficult to get
a DNA profile from. If you have a hair that is actually pulled out from somebody's head or wherever that hair is coming from,
and the root is still in the active growth phase, what happens is when the hair gets pulled out,
there's still tissue that's attached that's a really good source of DNA. So it was my role to go through the hairs in this case
and there were hundreds of them. I went through more than 200 hairs, in this case,
and was able to identify a handful for DNA analysis. Most of the hairs that I did DNA analysis on
came back to the victim in this case, but there was one hair that had a profile from an unknown male.
It didn't match any of the other reference samples from other potential suspects that were in the case.
And so what I do is I write my report, say there's a profile, it doesn't match the victim.
It doesn't match any of these other individuals. And then the profile was entered into CODIS.
NANCY GRACE: Police working on Diane Dahn's case submitted DNA sample from the suspected killer into CODIS,
the national database of DNA profiles from convicted offenders. So the DNA that was identified was a partial profile that
was suitable for CODIS entry, and it was put into CODIS, and there was never a hit.
The problem with the CODIS database is whilst it has 20 million people in it, the overwhelming crime, doesn't matter where in the world,
is generally committed by males between the age of 15 and 35. The CODIS database was started back in the mid 90s.
It's aging out. In other words, those people that are in the database the longest, they're not
going to be committing crime. They may have died. So they've become less useful.
So even though it has 20 million people, it's aging off, so it's going to become potentially
less relevant over time. After exhausting all leads and all the potential suspects,
and once DNA came about and they were able to eliminate all the people that they thought were suspects,
there was no other evidence. Ultimately, once everything has been exhausted, all the leads, all the evidence has been processed,
it goes cold and goes into the archives. It's a kind of a misnomer. When people say it's cold, people kind of think that we
don't ever look at it again. That's not true. It's cold in the sense that there is not an active daily investigation
barring new leads. But if there are new leads, then that becomes a warm case again.
And at any point, these cold cases can get reviewed given new evidence, and that's what's very exciting about investigative
genetic genealogy. It gives us the opportunity to kind of reclaim these cold cases and resolve them in a way
that we probably couldn't have before. Can investigative genetic genealogy ID Diane Dahn's
killer? We find out next on "Bloodline Detectives." [THEME MUSIC] NANCY GRACE: It's now over 20 years since the 1988
murder of 29-year-old single mom Diane Dahn, Santee, California. The case remains cold until detectives
turn to a new forensic science, investigative genetic genealogy. So genetic genealogy is when you have a DNA profile
and you want to identify relatives of that DNA profile. And it started decades ago with people who were adoptees,
and they wanted to know who their biological family members were. In 2018, the Golden State Killer was identified
through genetic genealogy and that kind of opened the floodgates to use it for case investigations.
So myself and others in the homicide unit attended a briefing given by the FBI and people who worked
on the Golden State Killer case, where we were introduced to this way of solving cases that seemed unsolvable,
as long as you have the presence of DNA. The way it's used in terms of a criminal case
is you have a DNA profile that's unknown and you want to know who are the family
members of this individual. And by creating those family trees, getting those connections, you can potentially
identify that unknown person. The science of investigative genetic genealogy is really expensive and it calls for great scientific expertise.
Normally, police departments outsource this research to professional labs, but the San Diego Sheriff's Department
tries a different approach. They want to learn these techniques for themselves and train their detectives to use
investigative genetic genealogy. So 2019, we kind of had either the arrogance or the chutzpah,
the naivete to decide that we were going to do this on our own. A lot of law enforcement agencies are using IGG.
Almost all of them farm out the genealogy part of it. We decided that it might be beneficial for us
if we could learn to do the genealogy. We go to a commercial company, they're going to build out this whole tree and take as much time
as it takes, and we're going to pay for that. Where I have my detectives and my analysts doing it,
let's say we have a high match. We have a third or fourth cousin to our person that we're looking for, either our victim or our suspect.
Well, through law enforcement databases, we can start looking at the people in that tree
and see who has ties to San Diego. So if we're looking at a case and we get a low match to say a third or fourth cousin,
and they're on the East Coast. And we start looking at that whole family tree and everyone's on the East Coast except cousin Bob, who
was in San Diego for four years in the Navy, well, we can jump straight to cousin Bob and start looking at him.
And see if he was in the area at the time, if any ties to our victim. So it actually saves a lot of time.
The team at San Diego Sheriff's Department begins the process of building the suspect's family tree.
They have a DNA sample retrieved from the crime scene. However, it does not match any known offenders.
Investigators now need to put the DNA sample in more databases besides CODIS. So IGG becomes appropriate when you have the presence
of DNA, you have had no hits in the CODIS database, and you have the potential to have a private lab examine
your DNA, process it so that it's in a form that could be read by the genealogical databases
that we're allowed to use. And then the last hurdle that they have to meet is is there enough extracted DNA left that we can send
it out for genetic genealogy? When I go from quant to amplification, sometimes when I do that step, I consume my sample.
I use all of the DNA that I have to try to get a profile. In this particular case, I had enough DNA
to attempt to get a profile, and there was still enough DNA left over. And so we were able to take that remaining extracted DNA
and send it off for genetic genealogy. We had a private lab do the SNP analysis.
Single nucleotide polymorphisms, SNPs. We share 99.7% of our DNA. That 0.3%, in a very general sense,
is it causes the difference between us. How you look, the color of your hair, the blue eyes, all of those things are because of SNPs.
They give us our diversity. So we take advantage of that diversity to help now say how much DNA do you share with someone else?
You can look anywhere between 10,000, which is what Berrigan developed, 10,000 SNPs, all the way up to 600,000, 700,000 SNPs.
You then upload that profile to GEDmatch. NANCY GRACE: GEDmatch is a California based
company that compares DNA data files from different testing companies. What's particularly unique about GEDmatch is that they
allow people or profiles from all the major genealogical companies to-- you can upload their kits and then match against everybody
else in their system. That's unique because if you do an Ancestry kit, you're only going to match against people
who have done another Ancestry kit in that world. But if you move an Ancestry kit to GEDmatch,
you can potentially match against somebody who did a 23 & Me or MyHeritage or Family Tree DNA.
NANCY GRACE: By 2020, the SNP analysis on the DNA sample is complete. Now the newly trained genealogist at San Diego
Sheriff's attempt to create a family tree using the refined DNA sample as a starting point.
We were fortunate that our initial high match, and what that means, whenever you're looking at how somebody
is related to somebody else, the shorthand that we use in genealogy is centimorgans,
which is basically just the genetic distance between two people. If you have a high centimorgan match that means
you're closer in relation than you are if you have a low centimorgan match. In Diane Dahn's case, we are fairly
fortunate in that our highest initial match was almost 200 centimorgans, so that would have indicated probably
a second cousin relationship. That's exciting because when you have that close of a relationship, you're
not going to have to necessarily go back 7, 8, 9 generations before you can move forward.
The next thing that we have to do is build trees, family trees. We have this known person, we have to start
building that family tree. We got very excited because this family among whom this match was from had a lot of connections
to San Diego. One of the benefits of doing all this in house is that we can consider things like geography and time
and people who are already in the case file. And obviously, this wider family had
a few known felons in the group, had deep San Diego connections. Who in the end, had absolutely nothing to do with the homicide
other than that they were related ultimately to the person who was responsible. It is painstaking work.
The team follows genetic lines, which, one by one, lead to dead ends. This is, in fact, progress because it's really
a process of elimination. Detectives know that each failure brings them one step closer to identifying
the correct genetic line. We worked a different side of the tree and that's where we discovered another group
of folks that also had a relationship to San Diego. But more specifically, a couple of people
had a relationship to Santee, and that became kind of key to us unlocking the identity of this case.
NANCY GRACE: Eventually, the Bloodline Detectives make a breakthrough. They identify a name, a man linked
to Santee, who detectives believe may be related to Diane Dahn's killer. He was related, funnily enough, to the high match
clearly, because this person was a high match, and I believe he ended up being a second cousin, which
confirmed for us kind of the initial work that we had done trying to figure out how is the high match related to this unknown person?
The suspect that we identified was Warren Robertson. NANCY GRACE: So who is Warren Robertson and where is he now?
We find out next on "Bloodline Detectives." [THEME MUSIC] NANCY GRACE: It's now 30 years since the brutal murder
of young mom Diane Dahn in Santee, California. Her brutalized body discovered in her apartment
while her two-year-old son Mark is there found wandering around covered in his mother's blood.
Now, new DNA technology gives genealogists at the San Diego Sheriff's the name of a prime suspect,
Warren Robertson. We had a suspicion that Warren, just based on information that we
were able to gather about where he lived in the 80s and where he was in the family tree,
that this was somebody that we should look into more clearly. As we eliminated other people, at some point,
we were only left with Warren as a possible suspect. But that's not proof just thinking
that it had to have been him. You have to go out somehow and connect him genetically
to the DNA left at the scene. As police attempt to connect Robertson to the murderer,
they inform Diane Dahn's son Mark of the latest breakthrough. Mark doesn't remember his mother's
murder despite having been in the apartment the night she's killed. I was on my way to the coast, of all places,
and while driving, I got a text message, and I gave him a call. And he kind of gave me a brief description of what was
going on, and I was in shock. And, you know, that's when all the anxiety and the excitement
kind of kicked in. What's going on? What did they find? How did they even do anything?
Why did it take so long? A lot of questions popped up. But then I was able to have a video call with him,
and he explained things further about the genealogy and how they were going through people's trashes
and collecting DNA samples. And I thought, my god, you've got to be kidding me? Like, all of that stuff is now possible
and it just blew my mind. It really blew my mind. NANCY GRACE: The Bloodline Detectives
need to connect the DNA sample from the crime scene with Warren Robertson's DNA.
As they close in on Robertson, investigators dig deep into his lifestyle. Warren was born in Arkansas.
He came out here. He was living here. He met his wife. He had a son. He was into drugs.
He was using drugs. His wife ultimately left him with their son, and then he had been arrested several times
for some petty drug stuff, property crimes. It appears that he lived in the same apartment complex
as Diane did at the time. We spoke to relatives of Warren that also lived there,
and they confirmed that they all lived there in that same complex. And he lived in a building just off of hers
where he could see her. He had moved out of the area at some point after the murder,
but not right after the murder. Had moved to the Midwest. As is the case with many older cases,
Warren Robertson had died in a house fire in 1999. NANCY GRACE: Warren Robertson's death in a house fire
means that Diane Dahn's likely killer has evaded justice. It's a setback. That's true.
But it's not the end of this investigation. We identified the suspect's children.
We had identified his ex-wife and the wife he was married to when he died, and we picked up the phone
and called his son and told him this extraordinary story. But we weren't just interested in telling a story.
We were interested in getting his DNA. Because if we could get his DNA, and we could match
it to suspect DNA, then we knew that we had arrived at the right person. In the son's case, and in others that we talked to about him,
they were happy to help. He really didn't have a relationship with his father, and he, like most people that we talked to,
wanted to know the truth. He said, I don't want to think of my father as somebody who killed somebody, but if he did,
I don't want to stand in the way of having that fact come out. So he agreed to cooperate and help us.
What the detectives had to do was to get DNA samples from family members of the individual,
and then I would do a type of paternity analysis that involves his child and the child's mother
and see if whoever is the owner of the DNA on that hair, could that individual be the father of this profile
that I obtained from a particular individual? So it's a paternity analysis is what we call it.
A vicious murder is so close to being solved. Will a son, now a man, soon have more answers
than questions about what happened to his mother? That's next on "Bloodline Detectives."
[THEME MUSIC] NANCY GRACE: San Diego, California. After over 30 years, thousands of hours of police work,
detectives finally get the news that they've waited so long to hear, the identity of the man who
murdered young mom Diane Dahn. He supplied his DNA and they examined it in the crime lab.
Even though they don't do SNP analysis, they can do Y-STR analysis, where they can see that there
is an extraordinarily high probability that the DNA of the son is related to this unknown DNA.
And that was true, leading us to target Warren Robertson as the suspect and as the person responsible
for the murder of Diane Dahn. NANCY GRACE: One of the first people detectives inform of the breakthrough
is Mark, Diane's son. It was just a text message, and I thought to myself, OK, that's interesting.
And then I got a look at the guy. He had sent me from previous times this is who he suspected,
so I had a picture of him. And then later on, we had a conversation on the phone
about who he was and why he did what he did hypothetically, or a theory as to why he did what he did.
And it turns out he was just kind of a guy who was probably on drugs and just kind of went on a spree
going through the apartments and she was collateral damage. It brings closure, I guess.
In a weird way, it was more like that makes sense, rather than having question after question
as to why this was there. Why did this happen? It was more, that makes sense. It's not right, but at least I have answers to the questions
that I've had for so long. NANCY GRACE: San Diego Sheriff's go public with the news this cold case has finally been solved.
At an emotionally charged news conference, Diane's sister Victoria says she never gave up
hope that this day would eventually come. I'm so grateful to the detectives and everything
that has been done. I didn't think anything was ever going to come of this. The detectives have done such a wonderful job.
I can't even begin to give them enough praise. Detective Patterson was persistent,
and when he came back and said that they got a hit, it probably was, other than the birth of my children,
the best day of my life. NANCY GRACE: Investigators reflect on lessons they learned.
They believe that training their staff to utilize investigative genetic genealogy techniques
is a game changer. The San Diego Sheriff's Department, we're very lucky. Is we have a large department with a very good budget,
but we don't have a huge crime rate like Chicago or LA or New York, so we have time to work
our cases very, very in-depth. Not to say that they don't, but we're able to put four detectives focusing on this type of stuff.
And I still have enough detectives to do work in all the other current homicides.
You have to have the resources and the and the financial ability to do it. And then having your own crime lab,
we're able to cut down a lot of cost too instead of having to farm everything out.
We've been working this four years, and I think up to this point, we have resolved nine cases,
and we are actively working a half a dozen more. And there are a lot of other cases that are in line.
We're very to moderately close on four other cases, and we hope to be able to make more
announcements in the future. Now that we're comfortable as investigators, as analysts,
as we sort of deepen our knowledge and our training about genealogy, we will get you.
Maybe not today, maybe not tomorrow, but we will get you. Investigative genetic genealogy
is a game changer thanks to the increasing number of people who test their own genetic makeup.
The results of these tests in large databases can help law enforcement crack seemingly uncrackable cases.
If I look back at my life, as much as I would have loved to have spent time with her,
everything happens for a reason. And when I say that, I mean, because of the things that have
happened to me, that's what made me who I am today, who I feel is a pretty good person.
And without those things, maybe it would have been better, maybe it would have been worse, but I
am who I am today because of all of the things that have happened to me. No matter how big of a trauma it seems in the moment,
it's going to make you into something great if you allow it. What's so remarkable about investigative genetic genealogy
is that criminals who think they've gotten away with murder now find there is no hiding from science
and their own family's DNA. The next knock on their door may be Lady Justice serving it up,
even after 30 years. I'm Nancy Grace. Thank you for being with us here on "Bloodline Detectives."
[THEME MUSIC]

In 1988, a 2-year-old is discovered walking around an apartment alone in Santee, San Diego. His mother lies dead in a nearby bedroom. 34 years later, investigative genetic genealogy finally names the man who killed Diane Dahn.

Now in its fourth season, Bloodline Detectives is the leading true crime series that explores how police departments harness genetic genealogy to solve crimes that were once considered "unsolvable," bringing long-awaited answers to victims' families.

=============== Like, comment and subscribe if you’re ready for more true crime. Your favorite shows like World’s Most Evil Killers, Meet Marry Murder, Forensic Files, Unsolved Mysteries, Murdered At First Sight and Bloodline Detectives are all available to stream 24/7 for free via the FilmRise Streaming Network. You can access The FilmRise Streaming Network through most free App Platforms and Smart TV portals such as Amazon Fire TV, The Roku Channel, Android, iOS and many more.

Brief Summary

The 1988 murder of Diane Dahn is solved using DNA technology, revealing her son Mark's emotional journey for answers.

Key points

A Breakthrough in Forensics. Thirty years later, new forensic technology offers hope in solving Diane Dahn's cold case.
The Murder of Diane Dahn. In May 1988, young mom Diane Dahn is found murdered in her home, leaving her toddler son Mark to grapple with the aftermath.
The Role of Genetic Genealogy. Detectives turn to investigative genetic genealogy to potentially identify Diane Dahn's killer after decades of cold leads.
DNA Technology Revolutionizes Investigation. New DNA technology aids in solving the cold case of Diane Dahn.
Breakthrough in Cold Case. Detectives identify Warren Robertson as the prime suspect in Diane Dahn's murder after 30 years.
Closure After Decades. Diane's sister expresses gratitude and relief after the case is solved.

Episode highlights

Episode quotes

Why didn't I die?

Gary Beyer reflects on the traumatic discovery of Diane Dahn's body.

0:59WatchJul 25, 2024

Tension

75/ 100High tension

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