Don was a second-year medical resident intending to specialize in pediatrics. He lived with his wife, Carrie, and their children, Abby and Joshua, in Washington D.C. On the night of March 9, 1985, when Donald had gone to sleep on the couch after an argument, a resentful former resident of the house, James Stanworth, broke into the house along with two local petty thieves, Mary Rutka and Thomas "Tommy" Wittman, knocked down and stabbed Donald non-fatally and killed Carrie and Abby, leaving Joshua alive on Mary's request. When the police started investigating, Donald told them what had happened. But when he at first forgot to mention that a woman was present, they became increasingly suspicious. The investigation came to the conclusion that Donald had killed his wife and daughter and injured himself to make himself look like a victim; it was argued that, being a medical student, he would have the knowledge and skills required to do so.
At the trial, the prosecution claimed that Don had suffered an acute psychological break and was a psychopath who wouldn't be able to control his murderous urges. He was sentenced to life with the possibility of parole in 25 years. While in prison, he became a model inmate. He even started a mentor program that helped 41 inmates get their General Education Diplomas. When he realized that Tommy, who worked at the local grocery store where the Sandersons had frequently shopped at, had been present during the attack, he began using his Internet privileges to do research about him online. When James, who had become a successful businessman and congressional candidate, found out, he arranged to have a stash of heroin planted in Don's cell, successfully getting his Internet privileges revoked. Don decided to improvise, continuing to be a model inmate.
25 to LifeEdit
Eventually, the prison staff contemplates giving him his chance of parole prematurely, but they are still suspicious and request the BAU to send an agent in to interview him. Morgan is given the task, and after interrogating Don, who tells him that he regrets murdering Carrie and Abby, he believes that he deserves to be paroled and argues his case to the staff. The staff, in turn, accepts the response and paroles Donald. Two days later, Don tracks down Tom and holds him at gunpoint, presumably to demand information. However, Tommy fights back and Don is forced to fatally stab him with one of Tommy's kitchen knives in self-defense. Ironically, since James stabbed Carrie and Abby to death, local authorities immediately suspected Don of succumbing to his murderous urges. Morgan is especially outraged and initially doesn't listen to Don when he tries to state that his murder of Tommy was self-defense and that he didn't kill Carrie and Abby. But Morgan and Rossi eventually listen and take Don back to the old Sanderson residence, where he reminisces of the time James, Mary, and Tommy broke into the home, telling everything to the two of them. When Mary is murdered by James (who, in turn, is eventually arrested by Morgan and the BAU), Garcia manages to track down Joshua, who has a joyous reunion with Don as Morgan watches.
- December 7, 2010: Tommy Wittman (was stabbed to death in self-defense)