The Hike-In Arsonist
Marin County, California 1987-1991
This case history is from the archives. A contributor to this is Jack Rosevear. Joseph Konefal and Ed Nordskog were historical researchers and authors.
From 1987-1991, the wildlands of Marin County, California were plagued with an expanding list of suspicious wildland fires. These fires caught the attention of investigators from multiple agencies. The fires were among some of the most unique events in California history. They were not unique based on their size, or the damage they did, or even the number of them. The unique aspect of these fires was based on two factors not normally seen in wildfires. First, the fires all originated deep into the wildlands, and not along any road as is typical in most wildland arson series. Secondly, the unknown suspect was using a delay incendiary device unlike any previously discovered in the state (or seen since these events). In 2023, retired Marin County Fire Marshal/Investigator Jack Rosevear recounted the details of this extraordinary case.
Rosevear recalled that by 1991, he was one of the lead investigators for a series of more than 40 fires dating back several years. The case was so important that a local task force was formed specifically to deal with it. It became a joint investigation by Marin County Fire and Sheriff’s Departments, as well as the specialized “arson/surveillance” unit from the California Dept. of Forestry (CDF), now known as Cal FIRE.
At the same time as the wildfires, there were numerous structure arson fires in the area as well, including several arson/burglaries at area high schools. Frustrated fire investigators began seriously considering the possibility that one of their own firefighters was lighting the fires. They took the extraordinary steps of fingerprinting and photographing all area firefighters.
Inv. Rosevear took the rare step to reach out to the FBI Behavior Analysis Unit (profilers) to develop a potential suspect. After presenting his case to several agents, he was less than enthused at their focus. It appeared that the agents were more interested in the possibility that this unknown arsonist may be building up to be a serial killer, than how to identify him for his arson crimes. [Nordskog-It was erroneously accepted in those days by lots of people that all serial killers started out as serial arsonists. Later research has debunked that myth…but many pseudo-experts still believe it.] The arson task force was more enthused with a local fire investigator’s assessment of the unknown arsonist. The local expert, using merely common sense and his own experience opined that this arsonist was likely someone local who investigators probably already knew. This unknown sage ended up being “spot on”.
In 1991, a local man named Thayne Dawson was arrested with a few other young men in relation to a burglary/arson at an area school. After the group was released from jail pending trial, police investigators “flipped” at least two of the young men into informants. They told a compelling story about 20-year-old Thayne Dawson.
In short, Dawson was a long-time serial arsonist with at least two prior convictions for arson, dating back to when he was ten years old when he set a vegetation fire. Five years later in 1986 at age 15, Dawson was arrested after he set a fire in his high school. By 1991, he was involved with the others in setting several fires in area schools.
The informants then added that Dawson had set dozens of wildland fires over the years. He had developed and used regularly a delay incendiary device that he carried with him to the fire scenes. The device was a small paper box similar to a milk carton that held a candle and an amount of floral foam. That item was then placed inside of a second carboard box. This prevented wind from blowing the candle out. The device provided a long-term (up to four hours) delay. The innocent looking device components were carried by Dawson to the scenes of his fires. He lit the candle and simply walked away. Eventually (the delay was based on the height of the candle) the candle burned down, ignited the floral foam, which then ignited the milk carton and the surrounding cardboard box. This item provided enough of a flame source to ignite any combustible materials near it.
The genius of this item lied within its simplicity and reliability. A second factor was that if it worked properly, the device typically consumed itself when it functioned, which basically made it an extremely rare “anti-forensics” device. The device was extremely cheap to make as Dawson usually purchased the inexpensive components at a strip mall near his home. He also scrounged through trash bins behind the strip mall for the milk cartons and cardboard.
The two informants then told police that Dawson had used the device in multiple arson fires set within area schools and other buildings. He had also hiked deep into the hills in the area and had set several large brush fires with the same style device. The arson investigators were impressed by this information as they had recovered some cardboard remains at an arson scene within a school a few years earlier. They successfully recovered fingerprints off the cardboard they found at that scene, but the case was still unsolved as they had no one to compare the prints to. Now, they were able to compare the earlier prints to those of Thayne Dawson and got a positive forensic match.
The informants added that Dawson was extremely mobile and very physically fit. He rode his bike everywhere and when he set his wildland fires, he hiked deep into the hills to do so. This information matched the unsolved spate of wildland arson fires. The informants described Dawson as very paranoid and was constantly looking to see if he was being followed by investigators. He was going to be a very difficult person to surveille. The investigators knew at this point that they were dealing with an extraordinary arsonist. They began referring to Dawson by a nickname, The Hike-In Arsonist.
The informants said that Dawson frequently bragged about his fires to them, and that in the upcoming summer of 1992 he had plans to set a large wildfire to a local landmark, Mt. Tamalpais. The fire was planned for the Memorial Day weekend of 1992. The investigators knew that the slopes surrounding “Mt. Tam” were thick with dry brush and large trees, and that the public areas around that landmark would be filled with picknickers, hikers, and visitors that holiday weekend.
Investigators completed a detailed background investigation into Thayne Dawson. He had many traits consistent with other serial arsonists. He was described as paranoid, angry, and frustrated, and was currently seeing a mental health specialist. Dawson lived and worked very close to the fire scenes and even had an observable “handicap”. Dawson was deaf, and wore visible hearing aids. He had been identified by witnesses who described a young man wearing hearing aids at previous wildland fires.
Operation Big Foot
Leading up to the 1992 Memorial Day weekend, the task force of CDF and Marin FD/SD investigators devised a surveillance operation to follow Dawson (who was still out on bail). They expected him to attempt to use an incendiary device to set a large fire near Mt. Tam that weekend. The surveillance op involved the CDF surveillance team, multiple aerial assets, and investigators from both the Marin County Fire and Sheriff’s Departments following in vehicles. The surveillance was dubbed Operation Big Foot.
The surveillance plan called for the team to follow Dawson as he gathered materials for his incendiary device and proceeded to the wildlands area. From there he would be followed by aerial assets. The plan called for the investigators to not intervene at this point, but to let Dawson enter the wildlands and emerge at some other time. Again, the plan was specific that Dawson was not to be arrested at this point. He would be allowed to leave the area while investigators entered the woods to attempt to find and disable his incendiary device. According to the ops plan, Dawson would be arrested at a different time and place.
However, before this operation could be implemented, a great deal of controversy and argument between investigators ensued. Some of the local fire chiefs, along with a prosecutor lobbied for this operation to commence so they could catch Dawson in the act of lighting a wildfire. While they clearly had good evidence on Dawson for past arson fires, the prosecutor “wanted more”.
Some of the other investigators argued that they had sufficient evidence with the confirmed fingerprints and cooperating informants to charge Dawson for several previous fires. They argued that it was unnecessary and too risky to allow Dawson to ignite what could be a catastrophic fire on a busy holiday weekend. Inv. Rosevear remembered years later that the arguments got very heated about whether to conduct the operation or not. The suppression chiefs, not being investigators had the belief that the only ways to prosecute an arsonist was to either catch them in the act or to obtain a confession. They had no concept of modern criminal investigation, forensics, or case building techniques.
In the end, someone made the correct and ethical decision. The surveillance op was canceled and Dawson was arrested and charged for his previous fires. He eventually pleaded guilty to multiple counts of arson. He was sentenced to four years in state prison. After his release, the local investigators never heard from him again.
Thayne Dawson, aka the Hike-In Arsonist, was suspected of 42 fires in both structures and the wildlands. His M.O. was very unique compared with most other wildland arsonists, and his incendiary device was one of a kind. We would rate him as a “highly sophisticated” serial arsonist, despite his very young age.
The attached photos are courtesy of Jack Rosevear.