William was a veteran of the Second Gulf War serving with the U.S. Army. He had his left leg blown off by a roadside bomb, and subsequently received an honorable discharge. His sister, Lee, had been working the streets of Detroit as a prostitute until William found her one night. He offered her shelter and a shoulder to lean on. He convinced her to move back in with their mother Maxine, giving Lee his dog tags as a sign of faith. Shortly thereafter, she disappeared again. William then began searching for her, fearing the worst. He searched all of the neighborhoods she frequented, keeping tabs on the homeless people who also lived there. He began keeping tabs on certain prostitutes and drug addicts in the area, and began noticing that ten of them, including his sister, had disappeared. After having gone to the local Detroit Police, who then ignored this fact, William took it upon himself to get the FBI involved.
To Hell and Back
William is first seen visiting several locations in search of various contacts he had made on the streets. When he notices they are disappearing, he heads for the US/Canadian border. He successfully passes a customs check point, drives ahead, then stops. When he is told to move, he does a U-turn and heads straight for the guard shack. He doesn't appear to have any malice, as he gives the guards enough time to escape the shack before ramming right into it, destroying the shack and injuring himself in the process. The customs agents surround the car, demanding he exit. As he is being arrested, he tells them he has killed ten people, and that their photos are in his car. A customs agent searches his car and finds the photos of ten people. William says he has been killing them and taking them across the border. He then demands to speak to the FBI.
The BAU arrive shortly after, and Hotch watches him through the interrogation room window. Meanwhile, Prentiss and Morgan begin interviewing people in Detroit, showing them the photos William has collected. Hotch finally enters the interrogation room, and demands a confession and the locations of the bodies. He learns that William has been doing "head counts" of Lee's friends on the street. He has been tracking the movements of the real unsub, and went to the border to attract the attention of the FBI. Realizing that William is not the unsub, Hotch asks the local authorities to release him to their custody to help them with their investigation. He and William meet Prentiss, Morgan, and Detective Benning in Detroit and begin questioning the local homeless population.
A homeless man named Walter explains the habits of the area's homeless people, telling them that they cashed their welfare checks at a local motel. They also interview a hooker, who tells them that Lee wasn't a "working girl"; only that she turned tricks when she couldn't find regular work. She also explains that she hasn't seen Lee or a few other girls in awhile. They are given the identity of a girl named Kelly, and the location of the motel. At the motel, William and the team find that local drug dealers hang out in the area to solicit recent check cashers. They got a description of the vehicle that is most commonly seen, and Garcia IDs the owner as Mason Turner. William suggests that the unsub may be using the Civil War Underground Railroad to cross the border unnoticed. He and the team find the unsub's car near the river, and proceed across the border to Mason Turner's farm.
At the farm, they find Mason lying in bed, surrounded by medical equipment. The team investigates while Hightower waits with the local Canadian Police. Shortly after, Morgan and Prentiss find a bin filled with almost one hundred pairs of shoes; those of the victims. Prentiss asks William what kind of shoes his sister Lee wore. Later, Morgan returns from the search of the local woods. He comes to William, who is sitting near an ambulance. Offering some comfort, he hands William his dog tags (the ones William gave to his sister). William then realizes that Lee is dead. He goes near the house, listening to the conversation between Rossi and Mason. He hears Mason's reasons for having the victims abducted and that they are just "whores and drugs addicts; no one will miss them". Considering Mason's condition (both mentally and physically), Rossi says he believes that Mason will "get away with it". William overhears this also, and is secretly enraged.
When the investigation is over, and the real killer, Mason's autistic brother Lucas, is found, William grabs an abandoned Remington 870 shotgun from the porch and enters the house. He points the gun at Mason, who smiles in relief, and pulls the trigger. He is then arrested by JJ.
- May 20, 2009: Mason Turner