"No, it's not crazy. It's fate."
On May 11, 1979, when Bill was six years old, he and a friend named Quentin "Randy" Hartway somehow became lost in the forest during an elementary school field trip with their parents as chaperones. Since it was snowing, he and Randy decided to split up in order to find their way back and cover more ground. In the end, Bill was rescued, but Randy froze to death in the snow. This incident attracted a lot of public blame directed towards Bill, apparently because he was supposed to be responsible for Randy's well-being. The entire ordeal led to him to him being diagnosed with post-traumatic stress disorder and requiring him to take anti-depressants for most of his life. While he was still hospitalized, he received a storybook from his empathetic teacher, which was focused on Greek mythology. The storybook included a picture of the Labyrinth, an elaborate maze that closely resembled the forest he and Randy got lost in. As a result, Bill became entranced with Greek mythology and had since came to possess an intimate amount of knowledge on the subject.
In his adult years, he became a shipyard worker. In June 1994, he planned to retire and travel to Greece. However, his employer and friend, Wick Griffith, felt that Bill did not have the financial support needed for such a trip. He also felt that Bill was being held back by his sickly mother at the time and that he would have easily gotten lost in Greece. As a result, he got Bill drunk in order to prevent him from taking his flight. Unbeknownst to both of them, a shuttle bus, which Bill planned to use to ride to the airport, crashed on the way there, killing all five people aboard. In 2014, Bill managed to retire, but he was diagnosed with terminal mesothelioma, a rare form of cancer he contracted while working at the shipyard. Grief-stricken, he went to a café located across the street from the hospital where he was diagnosed, but couldn't muster the courage to get out of his car. Instead, Bill observed the customers, became jealous of their happiness, and decided to target several of them. He wrote down their license plates after they stepped out of the café and got their personal information from the local DMV. After stalking them for some time, he began sending them letters announcing their deaths before spiking their food or drinks with lethal amounts of arsenic, likely acquired from his workplace.
After claiming three victims this way, Bill sets his sights on Janice Cheswick in "Fatal". However, when she receives the letter he sent her, she calls 911 and winds up being rerouted to Rossi, who is investigating Bill's murders alongside the rest of the BAU. He warns her not to eat or drink anything; when she tosses away the wine he spiked, Bill is forced to personally kill her as Rossi is forced to listen. However, during the ensuing struggle, he suffers injuries to his hand. After he tends to his wounds at his residence, Bill receives a visit from Wick, who tells him of what he did twenty years ago. Horrified by this, Bill tries to kill Bonnie Taylor, another of his targets and a nurse at the hospital where he received his diagnosis, even sending her a letter, but he abandons the plan and decides to kill Wick instead. Approaching him at the shipyard, he gets him to drink some wine he spiked before they have a conversation on the docks. Bill tells him about what happened to him in his childhood and then rants to him about the importance of Greece to him. Then, he gives him a letter and picks up a tool when he tries to escape, threatening to stab him with it. Morgan and JJ then arrive and hold him at gunpoint; when he refuses to surrender, they tell him of the shuttle bus crash and that Bill would have died too had Wick not intervened. Shocked by this, Bill drops the tool and allows himself to be arrested, while Wick is guided to the hospital. Bill died off-screen from his cancer afterwards while incarcerated.
"It's FATE! Some are chosen, and some are not."
Bill randomly selected his victims from an entire line at a café that he went to a few weeks ago after being diagnosed with his disease. After writing down their license plates as they left the shop and finding their information from the DMV, he would then begin stalking them for some amount of time and interacted with them in some way before their deaths. He would then write them a letter (the words being written in block letters to disguise his handwriting) announcing their impending deaths and leave it in their mailboxes before spiking a food or drink they took with arsenic. With each murder, the time between him sending the letters and killing them decreased. In the case of the first two victims, he sent them a string of twine to their homes, but in the case of the last two, he left the twine on the bodies, which would match the age of the victims in length of centimeters. In the case of Janice Cheswick, he was not able to interact with her due to Rossi's call interfering with his M.O. Instead, he stabbed her with a knife and strangled her with the twine when she wouldn't ingest the arsenic meant for her.
The unsub is a white male who is aged in his 40s and has a large build. He is a highly organized offender, but it is not known about why or how he is choosing these victims. They appear to be killings of opportunity, and yet, he has also researched his targets as though they have been selected carefully and with premeditation. He leaves behind a piece of twine on the bodies of the victims, which seems to be an evident reference to the Three Fates, three goddess sisters found in Greek mythology, who decide a person's fate: Clotho, who spins the thread of life; Lachesis, who measures the thread; and finally, Atropos, who cuts the thread with shears at the moment of death. This is what the twine symbolizes to the unsub; he has decided the fate of the victims, and then, he observes them, as if he is assuming the form of a mythological god himself. It is unknown what triggered this spree, but the unsub may have suffered a loss and is now lashing out in rage, because if he cannot control his own fate, he will control the fate of others. He is also quite meticulous, since he studies his victims in advance to the murders, follows them, learns their habits, and even interacts with them. His need to have direct interactions with his victims is a compulsion that overrides his chances of being caught, and this compulsion will likely be his downfall and lead to his eventual capture. He is unraveling, however, as the time period between warning his victims and then killing them is getting shorter with each murder.
- April 24: Helen Mitchell
- April 29: Wayne Campbell
- April 30:
- Carlos Ortega
- Janice Cheswick (stabbed five times with a knife and fatally strangled with twine instead of being poisoned)
- May 1:
- Bonnie Taylor (intended; abandoned the plan when he focused on Wick Griffith instead)
- Wick Griffith (attempted, but survived; was poisoned, but later cured)
- Bill bears several similarities to serial killers Joe Smith and Chase Whitaker. All three were spree killers who learned that they were dying of a disease (Joe had a brain tumor, Chase had lymphoma, and Bill had terminal cancer), which would be one of the primary reasons they started killing victims. They would also later die of their respective illnesses after they were arrested.