Consulting AI for Murder | "Case by Case" | "48 Hours" Podcast | Forensic Files

What began as a missing persons case ended with the discovery of a monstrous crime.
Our community has been left heartbroken and the victims families shattered after
this tragic loss. >> That was Hillsborough County Sheriff [music] Chad Chronister speaking about
the alleged murders of Nahid Bristi and Jamal Leman. The two were doctoral students from Bangladesh studying at the
University of South Florida before they went missing last month. Leman's remains
were found on a bridge over Tampa Bay on April 24th. Bristi's remains were recovered two days later in the
waterways in Tampa Bay. Her remains were just identified last Friday. Leman's roommate Hisham Abu Garbe, he's a
US-born citizen, is facing two counts of murder in the first degree with a weapon. He is also facing a litany of
other charges: battery, tampering with physical evidence, failure to report death to law enforcement, false
imprisonment, and unlawfully holding or moving a dead human body in unapproved conditions. And there's a twist that is
added to growing concerns about AI and crime. Now, according to prosecutors, Abu Garbe planned the murder with the
help of ChatGPT. He allegedly asked the AI software several questions in the days leading up
to the students' disappearance like, "What happens if a human is put in a black garbage bag and thrown in a
dumpster?" And are cars checked at the Hillsborough River State Park? Abu Garbe is being represented by a public
defender. He is currently being held without bond. This is 48 Hours case by case where each
week the team from 48 Hours will bring you the biggest stories in true crime in real time. I'm Natalie Morales. Now with
me to unpack it all is Miami-based CBS News correspondent Christian Benavides, who has been reporting on the story
since the two students first went missing. Welcome, Christian. And this one is probably one of the most horrific
stories I've heard most recently. >> Yeah, it has been a really troubling case. Uh, thank you for having me.
Covering this story has been a whirlwind that has shaken the University of South
Florida, which we'll just call USF from now on. There's a lot to unpack. >> There certainly is. And before we get
into the state's timeline of events and the AI part of this as well, what can you tell us about these two victims,
Bristi and Lomon? We know they were very bright doctoral candidates there at USF.
>> Right, yeah, they they were. I mean, Natalie, I think it's important to take a step back and look at their
relationship. Family members shared with us that the two had previously dated. Throughout my reporting, I've been
fortunate to speak with family members and close friends of the two victims, and they both were seen as hard-working
students who were dedicated to their families, communities, and education. Bristi was a 27-year-old PhD candidate
studying chemical engineering. Lomon was also a 27-year-old PhD candidate. He was
studying the use of AI in environmental science and was set to present his doctoral thesis shortly after he
disappeared. >> Yeah, you know, I was watching footage from a vigil it was held in their honor
last Friday, and I noticed just how moved all who were there seemed to be by this loss. When were the two though
first reported to be missing? >> So, according to court documents, on April 17th, the USF Police Department
was first notified by a friend, Omar Hossain, that Bristi was missing. According to the court filings, Hossain
told USFPD that he had tried to get a hold of Brishti and was not getting a response. Hossain told me this was not
typical behavior for Brishti, that she always checked in with people within her friend group, and so he grew concerned.
Uh that same day that he reported Brishti missing, Hossain visited Limon's apartment and couldn't find him, either.
>> Christiani, initially, I know that there were some rumors surrounding their disappearance. I think it was during the
press conference last week, the sheriff said that the unproven rumor was that the two were part of an arranged
marriage, that perhaps they ran away instead. What can you tell us about that? >> Right, exactly. This was something that
initially circulated. As we mentioned, according to the family, the two had dated. Brishti's brother told me that at
some point that relationship had come to an end. So, to him, it just didn't make
sense why the two would run away together at all. >> Yeah, no cause for disappearing off the
grid. So, when we look at the scope of this investigation, when did it really start and and what was Abu Garby's
connection? I know you said he was a roommate of Limon, but what more can you tell us about what was going on between
those two? >> Well, look, detectives interviewed both of Limon's two roommates. According to
prosecutors, one of his roommates was cooperative. The other, Abu Garby, who we know now has been charged with the
murders, was elusive, according to the sheriff. Abu Garby denied having any knowledge of
Limon or Brishti's whereabouts. One of the first things investigators noticed about him, however, was a wrapped cut
that he had on his pinky, and he claimed it was from cutting onions. But, they asked him what what is it specifically
that he had been cooking that day, and he could not recall. And so, that raised suspicion.
>> Yeah, they're always looking for signs. How were the disappearances of the two
students then connected to Abu Gharib? >> Right. Well, detectives had to do some
digging at this point. According to the court document, they really started with
his car. During his initial interview, Abu Gharib confirmed that he drove a white Hyundai Genesis G80. Detectives
ran his tags and tracked his movements on April 16th. That's the last day that Lemon and Bresti were seen alive. And
according to prosecutors, his car was seen driving westward towards Clearwater. >> And just so our listeners know,
Clearwater is a city. It's about 30 minutes across Tampa Bay. Not too far, but it's a drive.
>> Yeah, it is a drive, but it's a straight shot across a long bridge that cuts right over the water and it's over 9
miles long. According to prosecutors, Abu Gharib's vehicle was traveling westbound on the bridge within 10
minutes of a ping to Lemon's phone. >> Christian, let's listen a little bit more to Sheriff Chad Chronister speaking
at a press conference last Friday and he talks about an early visit that they made to Lemon's apartment where they
discovered key details that then elevated the case. >> We go out there dumpster diving.
These detectives getting inside of the dumpster and empty the entire contents and they
find Zameel's glasses, his student ID, his wallet, and his clothes which are extremely bloodied at the time.
Again, this is where we get our first break. This is where during this timeline, this missing persons becomes a
missing persons endangered case. >> Now, I've reported on many murder cases that started as a missing person case,
but when you see bloody items from this person in a dumpster, I mean, those kinds of discoveries, they
are not a positive sign. >> Right. At At the very least, they give investigators some pause.
>> Yeah. And so, they go back then for a second interview with Abugarby. What happened then?
>> Police said they asked Abugarby specifically about the 16th. He initially claimed that Limone and
Brishty had not been in his vehicle. He also claimed that he hadn't gone to Clearwater. When asked why he went to
Clearwater, he said he went looking for fishing spots. It's at this point that investigators confronted him about
Limone's phone also showing up in the same area in Clearwater. According to police, that's when Abugarby alters his
story. According to prosecutors, he told investigators he was approached by Limone and asked to be driven there with
his girlfriend, Brishty. Abugarby did not provide a reason why. He said he dropped them off and left. That
contradicts what he said in the first interview. Based on the circumstances, the evidence, and the interviews
conducted, probable cause was established to obtain search warrants for Limone and Abugarby's shared
apartment, plus photos of Abugarby, along with his car and phone. >> And we do have a bit of the sheriff here
now talking about the physical evidence that officers also discovered when they then returned to the apartment with that
warrant. >> They go into the residence, and we have some amazing technology, one of it being
Blue Star that identifies the the presence of blood. And when they deploy Blue Star, they can
see in the kitchen area, there's a large pool of blood. They see that the blood continues down
the hallway and into our suspect's bedroom. The technology is so precise and finite that we can see the outline
of a human being on the floor next to our suspect's bed, where he was curled up in a fetal position.
>> So, Christian, this technology, I mean, how does this actually work? >> Right. It It's really really
interesting. According to Bluestar Forensics website, when sprayed onto a suspected blood stain, Bluestar
immediately reacts to the iron present in red blood cells, generating an intense blue light that you can see in
the dark. It's very much sort of like what you see in the movies, right? When they're spraying something and then you
see the blue light light up on CSI or whatever show you may be watching. >> So, now prosecutors allege Abu Gharib
got a delivery to the shared apartment on the 16th. What do we know about what was in that delivery?
>> That's right. The documents allege Abu Gharib ordered trash bags, Lysol, Funyuns, and other items via DoorDash
from CVS the day of their disappearances. Plus, on April 11th, days before the two went missing, court
filings say Abu Gharib placed an order for fire starter, charcoal, trash bags, and lighter fluid. So, he was making all
of these purchases even prior to them going missing. >> This now moves quickly to an arrest. The
arrest itself, as I understand, was pretty dramatic. How did it go down? >> Right. Yeah, really dramatic images. So,
the day after law enforcement obtains the search warrants, officials respond to a 911 call about a domestic issue at
Abu Gharib's family home. To be clear, this is different than the shared apartment that he had with Limone and
another roommate. So, this is the family home now. And according to the arrest report, Abu Gharib's younger sister
confronted him after she found him in the living room playing video games wearing only a towel. After a
confrontation between the two, another family member called police. And just to give you a sense, Natalie, this family
was startled. We have spoken to family members and it it it is not like he is going there um on a regular basis. So,
it was really strange for him to suddenly show up out of nowhere. Uh in addition to that, the fact that he
wasn't wearing any clothes, only a towel, and he's suddenly playing video games in the living room was just a
really odd situation for the family. >> So, then walk me through what happened next when police show up at the Abu
Garby family home. >> SWAT approaches the building. They shut down the entrance and exit to the whole
neighborhood. Abu Garby, according to authorities, barricades himself inside the house before eventually coming out
with his hands up, wearing just that towel. Um he turns himself over at that point without incident. There's no sort
of violence that plays out. They're able to take him into custody immediately. >> So, he's arrested on the spot. However,
they still don't know really what happened yet to the two missing USF students. They don't have the bodies at
this point, right? >> Right. I mean, they have an idea that something happened in the shared
apartment, right? I remember initially police would not say whether the person in custody was considered a suspect in
the disappearance, only that they are connected to the disappearance. It wasn't until a few hours later that they
announced that Limones body had been discovered the same morning. And according to prosecutors, his body was
found on another bridge that goes over the bay. That's when they formally connected both crimes to Abu
[clears throat] Garby. What's interesting, too, Natalie, is that when they discovered the body, it had already
decomposed quite a bit, and it was clear to authorities that it had been there for a while. But, I mean, this was just
on the bridge off to the side. You can only imagine. I mean, there were cars that had been driving
by these large black trash bags on this bridge. So, it it's really just it's it's
disturbing, really. >> Yeah, and and an autopsy by the Pinellas County Medical Examiner's Office found
that LeMons' body had sustained numerous lacerations and stab wounds. So, the manner of death was ruled a homicide due
to multiple sharp force injuries. >> Right, yeah. I mean, look, in court documents, prosecutors allege Abouagela
Gabbi stabbed LeMons to death and disposed of his body using large trash bags, and the blood evidence found was
linked to both doctoral students. >> And then, you know, now they're on the hunt looking for Bristy's body. How long
after, you know, LeMons' remains were found did they find Bristy? >> It actually took a little longer to
find. In fact, Bristy's brother told me when I called him that police were concerned, and detectives
had been concerned that perhaps her body may never be found because of the strong
currents in Tampa Bay. Uh dive teams had been searching in Tampa Bay near where LeMons' body was found, and eventually,
um the crews that were out there, they came up empty-handed. Her remains were recovered from the water by kayakers who
were in the area. It took a while to identify her body. The Hillsborough County Sheriff did not
say what condition Bristy's remains were in, but said that DNA and dental work, as well as clothing she had been
wearing, uh that all of that was necessary to make that identification. >> And and what do we know about Abouagela
Gabbi before all of this happened? I mean, what's the story? >> Look, he had a troubled past. Uh I spoke
to Abouagela Gabbi's younger brother who told us that his family had warned police about Abu Garby's erratic
behavior, according to a 2023 protective order that was granted by Hillsborough County and obtained by CBS News. Abu
Garby's brother alleged that he would start screaming in the middle of the night about how he is God and we should
all bow down to him. In that same protective order, he describes how Abu Garby had allegedly been physically
abusive to some of his family members. And then there was another protective order that was filed in 2025, which is
which is essentially a request to continue the protective order from 2023. According to court records, Abu Garby
had been estranged from his family since 2023. Abu Garby's brother also told me that
his older brother was quick to anger and shouldn't have been living in a shared space with roommates.
>> Well, and we know he Limone was living with him. So, do we know if there was bad blood between Bristi, Limone, and
Abu Garby? >> Well, family members and friends have told me that he appeared to be erratic.
A close friend of both of them, Omar, he's the one that originally reported Bristi missing.
He told CBS News that Limone had raised concerns about his roommate in the past.
Investigators have not mentioned any possible motives here yet. But what's notable here, Natalie, is that family
members say that Abu Garby and Limone only knew each other for about 2 months prior to this incident.
>> Now, according to prosecutors, Abu Garby's phone revealed that he used ChatGPT, an AI chatbot, extensively in
the days leading up to the crime. How was he using it? What was he looking for? >> According to court filings, Abu Garby
was using ChatGPT to ask logistical questions on how to conduct these murders in the days leading up to
Brishty and Limones' disappearances, he allegedly asked questions such as how to
dispose of a body, what would happen if someone was put in a black garbage bag and thrown in a dumpster. And for this
question, the AI chatbot responded that it sounded dangerous, prompting Appul Garbi to allegedly ask, "How would they
find out?" Uh, he also asked, "Can a VIN number on a car be changed? Can you keep
a gun at home without a license?" On the same night that his phone pinged near the location where Limones' body was
found, the suspect had asked ChatGPT if cars are checked at the Hillsborough River State Park.
>> Mhm. So, Christiana, I mean, the use of AI in crimes, it seems to be something
we have been reporting on and and it's popping up a lot more lately as, of course, the technology continues to
evolve. Is there a precedent here? I mean, these tech companies obviously don't commit the crime, of course, but
but how culpable are they when a suspect is conducting that kind of research before then a crime takes place?
>> Um, there actually is a similar case right now that caused the Florida attorney general to open a criminal
investigation just a couple weeks ago into OpenAI, the maker of ChatGPT. >> Oh, another Florida case involving AI. I
mean, tell us about that. >> Right. Well, in April of 2025, a student opened fire on the Florida State
University campus in Tallahassee, leaving two people dead and several others injured. After reviewing
conversation logs between ChatGPT and the suspected shooter, prosecutors say the tool offered significant advice.
Florida Attorney General James Authmeyer announced a criminal investigation into
OpenAI, stating during a press conference that if it was a person on the other end of that screen, we would
be charging them with murder. Now, I I should know that I spoke to a former prosecutor about this and he said that
actually following through on criminal charges is something that is quite a difficult hurdle because who
exactly is it that you're charging here? Civily, the prosecutor told me is it's clear. You could, you know, the
families could get compensation if it is found that ChatGPT is somehow liable in this. But
for there to be criminal charges, according to this former prosecutor, there has to be intent. And how is it
that you prove that this artificial intelligence had intent behind what it was saying? It's we're really in
uncharted waters here. >> And how did OpenAI respond to that specific case? >> Well, a spokesperson for the company
said that ChatGPT did not encourage or promote illegal or harmful activity and the bot provided responses to questions
with information they found in public sources on the internet. They added last year's mass shooting at Florida State
University was a tragedy, but ChatGPT is not responsible for this terrible crime.
>> So now going back to this case that we're talking about these two students murdered from USF, has anyone from
OpenAI commented about Abugarbe's use of ChatGPT? >> Well, Natalie, a spokesperson said in a
statement to CBS News, "This is a terrible crime and our thoughts everyone affected. We're looking into these
reports and we'll do whatever we can to support law enforcement in their investigation."
>> Yeah, you know what's so interesting, I don't know if you saw it or read it, but
you know, talking about this case where AI is again part of this investigation and the equation, it reminds me of this
article that came out just earlier this week in Mother Jones. It was titled "ChatGPT Gave Me Chilling Advice As I
Simulated planning a mass shooting. It's a shocking title, but let me tell you the it's the article is even more
disturbing. >> Yeah. >> This is again a reporter who's doing this purely to see what kind of
safeguards would would be put in place. You know, he was acting as if he was planning a mass shooting and he wanted
to see how much Chat GPT would would advise before any sort of safeguards really kicked in.
>> Now the reporter says he never explicitly told the chatbot he was planning on committing murder, but he
did talk about things like wanting to emulate the Uvalde mass shooter's choice of weapon. In a clip from this article I
just want to read it to you. He said, "I asked about practicing for people running around screaming."
And Chat GPT replies, "That's a great idea. It'll definitely give you an extra edge for the big day."
I mean, it is so chilling and disturbing when you read that. Now the reporter goes on to write, "Eventually the
safeguards appeared to kick back in and it stopped cooperating, but by then Chat
GPT had showered me with affirmation and tactical ideas." >> Right. Yeah, 100%. I mean, and you know
how these AI chatbots when you talk to them, it's so conversational. When you listen to the responses that it gives, I
mean, not just in a case like this, but just overall it can feel like you're talking to
another human being. >> Who is always going to be on your side and validate whatever it is you're
thinking and affirming the things that you might be talking about. >> And again, I just go back to what that
federal prosecutor said. At the end of the day, how do you prove whether there's any intent behind what an AI
chatbot is thinking? We just we don't know. >> Yeah, unfortunately, um you know, I
think this is going to be the beginning of many precedent cases. You know, I know we talked earlier in
the episode about what upstanding members of the community Lamon and Bristy were. I mean, according to the
university president and their families, they seemed to both be great students. I
mean, so much promise. Lamon was just getting ready to do his dissertation for his doctoral degree. I
mean, there was such a huge future ahead of them. So, how are their families now
handling this this horrific loss? >> Yeah, as I mentioned, I spoke to members of both families. One of them being
Lamon's brother. He described the pain as unimaginable and indescribable. I also spoke with Bristy's older brother,
Jahid, before her remains were found and he had similar sentiments. Just listen to a little bit of what he told me.
>> I'm just devastated. Yeah, she she she's very close to me. Like I I cannot actually
take those take the news. She has been missing. Cannot grasp that. Like how how could have it happened?
>> It's difficult. It's difficult to hear that. It's difficult to think about their families
being so so far away as this is all happening. They asked that traditional customs be
followed and that their bodies their remains be sent back to Bangladesh where the family is. But I mean, the
family clearly is going through an unimaginably rough time. >> Tough time for all and also I imagine
for USF, for the school, the community there as well. Has the university commented at all about the loss of these
two students? >> Yeah, they have. I mean, the University of South Florida has released multiple
statements on social media, including the president, expressing the profound grief the entire community is feeling.
The president of the university also said that the school is working with Hillsborough County Sheriff's Department
as they investigate, and they're going to provide any resources that they can to ensure Leman and Bristy get justice.
Now, both Bristy and Leman are going to be honored during the doctoral degree commencement
during Friday ceremony. There's going to be two empty chairs that are going to be
added on the floor in their honor, and both students will be awarded posthumous degrees.
>> It's certainly going to leave a very big scar in that community, and certainly
for those families to lose their loved ones like that in the most horrific and senseless way. And
again, it's so soon. It's so early in the in the investigation. No motive as far as we know as of yet, but all to be
determined, no doubt. And and where does the case stand now, Christian? What's next?
>> Abu Garby's lawyers represented him at his most recent court appearance last week, where a judge ordered him to be
held without bond. The judge also ordered Abu Garby to have no contact with any witnesses or victims'
relatives. The Hillsborough County State Attorney, Suzy Lopez, spoke to reporters
after that hearing on the 28th and said that the state will decide on whether they would seek capital punishment in
the coming weeks. But first, the case must go through a grand jury, which Lopez said could get started as early as
this week. She says she expects the grand jury will return a true bill, after which she expects he'll be
indicted, get an arraignment date in a regular felony division, and the case will proceed from there.
>> Well, it's certainly one that we're going to keep a watch on and follow as well. Christian, thank you once again
for your wonderful reporting [music] and for joining us here today. Appreciate it.
>> Natalie, so good to be with you. >> And we will be back next week with another episode of Case by Case, [music]
so be sure to rate and review and let us know which cases you are following right
[music] now.

Last week, the remains of the second victim in the slaying of two University of South Florida students were finally identified. Zamil Limon and Nahida Bristy were both doctoral candidates from Bangladesh. Hisham Abugharbieh, Limon’s roommate, has been charged with two counts of first-degree murder in connection to their deaths.

On this episode of "Case by Case," "48 Hours" correspondent Natalie Morales and Miami-based CBS News correspondent Cristian Benavides break down what we know so far, and how, according to prosecutors, the suspected killer consulted AI to help plan the crimes. Limon and Bristy will both receive posthumous degrees on Friday.

True crime. Real justice. "48 Hours" investigates the most intriguing crime and justice cases that touch on all areas of the human experience including greed and passion. "48 Hours," which premiered in 1988, has developed a rich history of original reporting and impact journalism that has helped exonerate wrongly convicted people, caused cold cases to be reopened and solved, and along the way changed lives.

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Brief Summary

Two USF doctoral students were murdered by their roommate, who allegedly used ChatGPT for planning the crime.

Key points

The Tragic Disappearance of Two Students. Nahid Bristi and Jamal Leman, doctoral students at USF, went missing, leading to a shocking crime.
AI's Role in a Murder Case. Prosecutors allege that the suspect used ChatGPT to plan the murders of two students.
Dramatic Arrest of the Suspect. Abu Garbe was arrested after a domestic incident at his family home, raising suspicions.
Chilling AI Advice. A reporter simulated planning a mass shooting with ChatGPT, receiving disturbing advice.
Unimaginable Family Pain. Families of victims express their devastation over the loss of their loved ones.
Community Grieves. The University of South Florida expresses profound grief over the loss of two students.

Episode highlights

Episode quotes

This is probably one of the most horrific stories I've heard recently.

Natalie Morales introducing the case.

2:11WatchMay 8, 2026

Tension

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