Not much is revealed about Ian's life prior to the events of Roadkill, except that he was married and served in the National Guard as a mechanic. On September 28, 2007, he was driving his wife Sheila's car, a red two-door coupé, along Route 7 in Bend, Oregon, at night with his wife who was sleeping. At some point on the trip, he apparently fell asleep at the wheel. As a result, the car slid off the road, flipping over a number of times. Sheila died and Ian suffered a spinal cord injury, which permanently disabled his legs. He received therapy, but the guilt he suffered, along with his developed post-traumatic stress disorder, caused him to reinterpret the whole accident as having been caused by a car similar to the one Sheila drove. He eventually became emotionally and mentally disturbed, drawing alarming sketches of weaponized automobiles during his time at a psychological therapeutic facility. In 2009, he sought revenge on the imaginary driver, looking for red coupés on his way to work. Whenever he saw one, he would stalk the victims for a while and then sabotage their cars to set up an ambush in some secluded area on Route 7. Within two weeks, he killed two women, Maria Delgado and Shannon Makely, the latter's murder being the one leading to the BAU being called in to help the local police department find the driver who was responsible.
Not knowing of the BAU's presence apparently, Ian begins to devolve, killing a man at a parking lot in front of a witness. Called in to investigate, the BAU make a profile that eventually leads them to Ian, who, at the time, is about to kill his fourth victim as he bikes with several others. As he is about to run him over, Hotch drives into the side of his car, stopping him but leaving both himself and Detective Quinn injured. Quinn confronts Ian with the truth, causing him to have a breakdown despite Hotch urging the detective not to, as Ian is mentally unstable and unpredictable. Ian, followed by Rossi and Morgan, speeds towards a cliff that he drives off of, committing suicide. Seconds before his death, Ian has an image of himself holding Sheila's hand, but in reality, he is cradling the bracelet she had worn before the crash.
The unsub is a white male in his early 40s, who is driven by revenge, has military experience (apparently from either the U.S. Army or Marine Corps), and was handicapped as a result of an automobile accident that occurred on Route 7, the same area where the unsub finds his victims. It is believed that he holds the driver of a red coupé responsible for the accident that caused him to become handicapped. This person is the object of his rage, but being unable to confront him or her, he is instead taking his revenge against surrogates. He may have gone to a local rehabilitation facility to recover from the accident. He would also have a lot of knowledge about car engines and hold a job where he is good with his hands, possibly like a mechanic.
Ian targeted people driving red coupés (the same type of car his wife drove), believing they were responsible for the car accident and his wife's death. He would stalk his victims and take pictures of them for a while after finding them. When he killed them, he would repeatedly drive over them with his car, a black Dodge D100 pickup truck from 1979, customized to fit his handicap. His first two victims were killed on Route 7, the street they usually drove on and where his accident occurred.
While Maria Delgado's murder was less sophisticated and involved him lying in wait at a trail where she was jogging, he sabotaged Shannon Makely's car so it would break down somewhere secluded on Route 7, to which he then killed her after she got out. Before he killed Victor Costella, he smashed the turn signals on the back of his car as a ruse, left filters he stripped off from cigarettes at the scene (a habit he learned from working for the National Guard), and waited for him in the parking garage of his workplace until he got to his car. After killing his victims, he would switch the grilles and license plates on his car to cover his tracks. The first two murders went without any witnesses due to the secluded areas where they occurred, but as Ian devolved, he began attacking his victims in more public places and with witnesses present.
Ian's killings could have been inspired by the unsolved murder of Spring Miller in Albuquerque, New Mexico, in 1988. Spring and her sister April were on a walk when they noticed a four-wheel drive vehicle waiting to leave a parking lot and stopped to let it pass, but the man at the wheel waved for them to go on. When they were in front of the vehicle, the driver grinned and accelerated to hit the girls, killing Spring and injuring April before fleeing. Miller's family believes that the killer was Martin C. Martinez, a motorist arrested six months later for deliberately running down joggers in the same area.
- September 28, 2007: Sheila Coakley (his wife; was accidentally killed in a car crash that he caused)
- April 18: Maria Delgado (killed while jogging on a lonely trail)
- April 30: Shannon Makely (cut the fuel line to her car, then killed her when she became stranded)
- May 1: Doctor Victor Costella (smashed the taillights of his car and killed in a parking garage in front of a witness)
- May 2: The biking trail attacks:
- Garret Burke (attempted to kill while he was biking with others)
- Numerous unnamed bikers (attempted, would have been collateral damage if he had succeeded in running over Garret Burke)
- Aaron Hotchner (attempted, but survived; accidentally rammed into his vehicle)
- Detective Quinn (first name unrevealed; attempted, but survived; accidentally rammed into Hotch's vehicle, then intended to run over)
- Ian has some similarities with Norman Hill, a spree killer in the Season Four episode Normal. Both were psychotic killers with stressors that involved the death of a close relative (for Ian, it was his wife; for Norman, it was his daughter) and were repeatedly haunted by hallucinations of their first victims. Both also targeted surrogates who represented the sources of their disillusionment with life: Norman targeted women who resembled his wife (who he perceived as emasculating him); while Ian targeted drivers of red coupes, since he believed the driver of a red coupe was responsible for his accident and wife's death.
- The song that Ian frequently listens to in his truck is "I'm Alive" by Johnny Thunder.