Forensic Files - Season 2, Episode 11 - Postal Mortem - Full Episode | Forensic Files

- So Steve, I see you had your breakfast of champions there with you? - Janet McDermott planned to stop by her office only briefly on the morning of
October 15th, 1985. - Have a nice day, Steve. - She had a number of business appointments around Salt Lake City that
day. [explosion] Moments later, an explosion rocked the building, killing her colleague who worked
next door. Science uncovered a tale of forgery, fraud and murder. b b - The explosion occured on the sixth floor of the historic Judge building in downtown
Salt Lake City. Killed in the blast was 31-year old Steve Christensen, a financial
consultant who left behind his wife, Terri and a young family. - He was lying in the doorway of his office and he was lying on his right side,
burn marks on his face, smoke marks and blood. - The explosion ripped the door off it's hinges and the location of the debris told
investigators that the blast occured directly in front of Steve Christensen's office door.
- You could tell the precise location where the bomb exploded. Match that with the autopsy and we could tell where the bomb was when it exploded because of its
sheering power, breaking bones, going through skin, things of that nature. - Small pieces of batteries and fragments of pipe were found in the hallway as well.
Many of the parts had the name Tandy imprinted, a brand sold exclusively in Radio Shack electronic stores. All of the fragments were collected and pieced back
together, revealing that the explosion was caused by a pipe bomb. This is a replica
of the type which was used. But who wanted to kill Steve Christensen and why? Christensen had recently resigned his job as Vice President of Consolidated
Financial Services or CFS, a real estate investment company which was undergoing
serious financial difficulties. Many clients had lost large sums of money and some were alleging fraud. In the debris, police discovered a piece of brown
wrapping paper with Christensen's first name written in thick black marker. Bruce
Passey had a jewelry business a few floors below Steve Christensen's office. He told
police he noticed something unusual in the elevator that morning. - I told them that I saw a box this morning that had the name Steve
Christensen and that my father and I went up in the elevator with the gentleman holding this box.
- Janet McDermott recalled seeing the package in the hallway directly in front of Steve Christensen's office door. A motion sensitive mercury switch was found
in the debris, an indication that the bomb was activated by tilting the package.
Motion-sensitive bombs are almost always delivered by the bombers themselves so they can be delivered without going off. Bruce Passey described the delivery man as
a white male, about 5'8" tall with medium brown hair. - Once he came in, I mean he was wearing a high school letter jacket without the
letter on it but it had the colors of a letter jacket. - I was just very concerned for the business community and that other people
might be involved on a revenge-type situation, whether it be for investments gone bad or something similar to that and I was
worried who would be the next victim. - That worry became reality just two hours later.
Two hours after the bombing which killed Steve Christensen, there was another explosion across town. This time the victim was 50-year old
Cathy Sheets. Her husband, Gary, was the former business partner of Steve Christensen.
- It was real devastating to have your mother killed on your front doorstep. You feel that you're safe in your home and that it's okay and to have something
like that happen really shattered your faith that things are okay. - Once again, the fragments recovered at the scene were consistent with the pipe
bomb. Police found scraps of brown paper near the blast with the name of the victim's husband, Gary Sheets.
- The time I got to the second scene, I already knew what I was looking for if there were going to be similarities. Within 25 minutes, I had found the
similarities. Within five hours, I found a component. That component was a very small
piece of a Mercury switch. - A Mercury switch was found at the Christensen bomb site as well.
A Mercury switch is a glass ball filled with Mercury, a liquid metal. When the Mercury is tilted, it completes the electrical circuit,
triggering the explosion. - We had a lot of similarities and they would include the cardboard container, the
types of tape, more than one type, the size of the pipe that which includes the diameter and the length. The explosive inside, the type of
explosives inside. - Gun powder from both bomb sites were sent to the Federal Bureau of Alcohol,
Tobacco and Firearms lab for analysis. They store samples of every known gun powder manufactured. The particles of gun powder from the pipe bombs were placed on
a profile projector, which measures the size and shape of the granules. When this
information was entered into a computer database, the gun powder was identified as
Hercules Bullseye brand. The same type was used in both bombs. Since Radio Shack
batteries and electrical components were found at both bomb sites, detectives checked all of the Radio Shack stores in the Salt Lake City area. Records showed
that an individual by the name of Mike Hansen had recently purchased the same components from this Radio Shack store in Holiday, Utah. The store had an address
for Mike Hansen but it was a vacant lot and detective suspected that the name was
an alias. The only individual who reported seeing anything suspicious at the Sheet's
home was a 13-year old neighbor, Aaron Taplick. He told police he saw a tan Toyota minivan turn into the Sheet's driveway around midnight, the night before
the bombing. He said the van drove out of the Sheet's driveway a few minutes later
but the boy could offer no description of the driver. - I think we have a serial bomber out there.
What was entering in my mind was how soon are we gonna have another bombing? - It was a very short wait.
While investigators were sifting through the rubble of the bombings which killed Steve Christensen and Cathy Sheets, there was a
third explosion the very next day. This time, it happened in a parked car in downtown Salt Lake City. The victim was 30-year old Mark Hoffman, a rare documents
dealer. Unlike the other two victims, Hoffman survived the blast. Hoffman's injuries were severe. The explosion blew off
the tips of two fingers, a portion of his right knee cap was missing and a piece of metal was imbedded in his knee.
- Mark Hoffman said that he pulled open the door and the package fell from the seat of the car onto the floorboard of the car, at which time it exploded
and he was injured. - Mark Hoffman had no connection with the CFS Corporation. He was a well known and
respected rare documents dealer who specialized in early Mormon currency and documents. But Mark Hoffman and Steve Christensen knew one another.
Christensen was a collector of rare books and documents and had purchased some items
from Hoffman over the years. One thing detectives knew, the bombs which killed Steve Christensen, Cathy Sheets, and seriously injured Mark Hoffman were all
made by the same individual. They also knew that evidence inside Mark Hoffman's car was inconsistent with what he told police. Hoffman said someone placed a
package on the seat of his car and when he opened the car door, the package fell onto
the floor and exploded. But when a pipe bomb explodes, the end caps blow out in a
straight line. One of the end caps blew a hole through the side door on the passenger side. The other end cap was found in Mark Hoffman's knee.
This important detail told investigators that the bomb did not explode on the floor
of the car as Hoffman indicated. - It didn't line up with the exploding bomb. We can't change that because of the
holes in the vehicle. That's the truth, it's not taking the injured pieces of the
individual, putting them so they come in contact with the bomb. - The injury to Hoffman's knee indicated that his right knee was on the driver seat
at the time of the explosion. And the injuries to Hoffman's fingers indicated that he had been touching the bomb when it exploded.
- So now we have an injured hand, an injured leg and I know the attitude the pipe bomb was in. I also know that he has uninjured body parts, the other
leg is in very good shape. There's not even any burn damage. So I have part of him outside the car, part of him inside the car.
- The evidence revealed that the bomb exploded over the center console, in between the two front seats and not on the floor of the vehicle
as Hoffman indicated. When police searched Mark Hoffman's home, they found a high school letter jacket
with the letter missing, similar to the one Bruce Passey saw on the delivery man
in the elevator on the morning of Steve Christensen's murder. Even more alarming, police discovered that Hoffman owned a tan colored
Toyota minivan similar to the one the teenage boy saw driving into the Sheets' driveway the night before the bombing.
Inside Hoffman's van, police discovered a single flake of gun powder. Tests revealed that it was Hercules Bullseye gun powder, the same type used
in making the pipe bombs. - We had no idea why Mark Hoffman, if he were the perpetrator, would kill a close
associate and friend of his, Steve Christensen. And for all we knew, he didn't even know Cathy Lee Sheets.
- Hoffman told police that he was a victim and even took a lie detector test to prove
his innocence. - We had him take a polygraph and he passed with flying colors. Not even close.
He passed with a high number saying that he was not deceptive and that he did not
do the bombings. - Despite the polygraph results, investigators were suspicious of Mark Hoffman since the scientific evidence was inconsistent
with his description of the bombing. On the day of Steve Christensen's murder, Mark Hoffman was scheduled to meet
with Mormon church officials to discuss some early Mormon documents he was selling
known as the McLelland collection. Steve Christensen was active in the Mormon church and was asked to attend that meeting in order to certify that the
documents were authentic. - As I was inquiring about who examined the documents, it was my feeling
it had never been examined forensically. - George Throckmorton was asked to do just that,
to use scientific forensic methods to find out whether some of the world's leading experts had been fooled.
Despite the fact that Mark Hoffman passed a lie detector test, bomb experts from the
Federal Bureau of Alcohol, Tobacco and Firearms were convinced that Mark Hoffman
was inside his automobile, possibly arming the bomb, when it accidentally exploded.
[explosion] The scientific evidence supported their theory but missing was a motive.
- How do you prove Mark Hoffman was a murderer is you first prove that he was a con-man, that his whole life was based upon fraud.
- George Throckmorton is a forensic document examiner who was asked to examine the rare documents Mark Hoffman had sold over the years.
He compared them to other rare documents the Mormon Church had in its vault from the same time period which Hoffman had nothing to do with.
Under ultraviolet light, many of the documents Hoffman sold turned blue. This was not the case with the documents the Mormon Church obtained
from other sources. Under a microscope, Throckmorton noticed that the ink on Hoffman's documents ran in one direction.
In the other documents, the ink was absorbed by the paper uniformly, spreading in all directions. And Throckmorton discovered
microscopic cracks in the ink on the documents Hoffman uncovered. Throckmorton calls it alligatoring and there was none of this
in any of the other documents. - At this point, it made us say something's wrong but we don't know what.
Why are Hoffman's documents different than the other documents? - When Mark Hoffman's home was searched following the bombings, police discovered
a book which contained a recipe for Irongallotannic ink, an ink that was common in the 1800s. Throckmorton made a batch of that ink and wrote with it on
some paper. He then applied an ammonious solution which is known to age paper. The test document displayed the same blue haze under ultraviolet light. And when it
was hung to dry, the ink ran in one direction and exhibited the same alligatoring condition as the Hoffman documents. Finally, Throckmorton turned
his attention to the Oath Of A Freeman, believed to be the oldest printed document
in the United States. It was a document Mark Hoffman said he purchased in a used
bookstore and was valued at over $1 million. It had been authenticated by both the Library of Congress and the FBI. When Throckmorton looked at it closely, he
found a curious anomaly, there was a tiny flaw in the letter M. - That microscopic flaw was not caused by old age, was not caused by a printing
problem, it was caused through the photographic process. Therefore that document had to go through that photographic process.
- The flaw looked like emulsion on a photographic negative. This modern printing method did not exist in 1638 when the Oath Of A Freeman was allegedly
written. - Therefore it had to be counterfeit. - Inside Hoffman's home, police discovered a receipt from a printing company in Utah.
It was for a printing plate for the Oath Of A Freeman document. The printing company thought the plate was used to print facsimiles. In fact it was.
Hoffman took the plate, added the old ink recipe and a piece of old paper to create
the forgery and offered it for sale as an original. On the receipt was the name Mike Hansen but it included Mark Hoffman's telephone number. It was the same name
used at the Radio Shack store to purchase the bomb components. Throckmorton's forensic document examination proved that Hoffman was a
fraud and a forger. Prosecuters believe that Steve Christensen was on to Mark Hoffman and was about to expose him as a liar and possibly a fraud.
Hoffman sensed this and decided to murder Steve Christensen with a pipe bomb. But Hoffman wanted Christensen's murder to appear to be business-related,
so he delivered a diversionary bomb to Christensen's former business partner, Gary Sheets.
The boy living across the street saw a van similar to Hoffman's pull into the Sheet's driveway around midnight.
Hoffman placed the pipe bomb package on the front walkway to the Sheets' home. The next morning, Hoffman delivered the primary bomb to Steve Christensen's office
building. It was packed with more than a hundred masonry nails, leaving no doubt
that its intent was to kill, not injure. The jewelry store owner identified Mark Hoffman as the man wearing the letter
jacket in the elevator. He was carrying a package addressed to Steve Christensen.
Hoffman left the package outside Christensen's office door. It was armed with a motion-sensitive Mercury switch set to explode
when tilted at a 45 degree angle. - Bye. Have a good day, Steve. - Steve Christensen picked up the package when he arrived for work.
[explosion] Two hours later, Cathy Sheets noticed the package left outside her home addressed to
her husband, Gary. [explosion] Mark Hoffman was arrested and charged with two counts of murder and for theft
by deception for selling forged documents. Hoffman pleaded guilty to second degree
murder and was convicted. A parole board recommended that he spend the rest of his
life in prison. Ironically, many of Hoffman's forgeries are still on the market.
- Every single document that I looked at had been forged or manipulated in some way
to make it valuable and I looked at over 600 of his documents. Every single one of
them was forged. He never found a single genuine document ever. - And the deception turned a mild mannered documents dealer into a killer.
- I think Mark is probably the most evil of people that I worked with. Serial bombers by and large are much more evil.
They don't want to just hurt you, they want to continue to hurt many people. - And how common is it for a bomber to blow himself up
when handling one of his own bombs? - Not common enough.

On October 15, 1985, two bomb explosions rocked Salt Lake City and resulted in two deaths. A third explosion occurred the next day; this time, the victim was injured but survived. As the investigation progressed, police came to believe the survivor was more than an innocent by-stander. When they turned to forensic science for help, they uncovered an almost unbelievable story of forgery, fraud and murder.

Forensic Files is the longest-running true crime series in television history. Evidence and interviews with experts help solve real crimes, disease outbreaks and accidents around the world.

Brief Summary

Mark Hoffman murdered Steve Christensen and Cathy Sheets using pipe bombs to hide his forgery scheme, leading to his conviction.

Key points

The Deadly Explosion. An explosion rocks a building, killing financial consultant Steve Christensen and revealing a web of deceit.
The Serial Bomber. Investigators suspect a serial bomber after a second explosion claims another victim, Cathy Sheets.
Mark Hoffman's Deception. Forensic examination reveals Mark Hoffman as a master forger, leading to his arrest for murder.

Episode highlights

Episode quotes

But who wanted to kill Steve Christensen and why?

2:20WatchMay 27, 2021

Tension

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