Authorities are hoping they have the answer to a question that has plagued them since early 2009: Who killed two mother-daughter pairs in a two-month period in suburban Maryland?
Jason Thomas Scott, 27, was charged today in the murder of Delores and Ebony Dewitt, a mother and daughter who were found in a burning car in March 2009. A Prince George's grand jury returned a seven-count indictment against Scott, including two counts of murder and two counts of burglary.
Law enforcement sources told ABC News that they believe Scott also killed Karen and Karissa Lofton two months prior in their locked home.
The horror began Jan. 26, 2009, in Prince Georges County, Maryland, as an intruder neutralized the Loftons' home alarm system and slipped inside.
Karen Lofton, a 45-year-old nurse, was fatally shot as she tried to hide in a corner. Her daughter Karissa, 16, was repeatedly shot as she frantically dialed 911 from her bed.
Police were perplexed. The doors were locked and there were no signs of forced entry. Neighbors were terrified.
"Until they catch him, I will be afraid," said one woman.
On March 16, the bodies of Delores Dewitt, a 42-year-old nurse, and her 20-year-old daughter, Ebony, were found in a burning car less than a mile away from the Loftons' home. The car had been stolen that day.
The Dewitts lived within a mile of the Loftons.
"She [Delores] was a beautiful person, had a beautiful spirit and was just a wonderful person all around. And so was Ebony," said a friend at a memorial service for the Dewitts.
"My heart is aching. I am hurting because I lost a friend," said another grieving attendee.
Authorities wondered whether this was the work of a serial killer. There were similarities -- two mother-daughter pairs; two nurses in their 40s -- but also stark differences. The Loftons were shot in their home in what appeared to be a controlled, planned execution. The Dewitts might have been killed in a random act of violence, perhaps a carjacking. It was unknown whether they had also been shot.
"We don't have any evidence this is a serial killer but the coincidences between these cases are very strong," said a police officer after the Dewitts' bodies were found.
An FBI profiler thought that the killer had acted differently in each case and that the cases were probably not linked. Still the residents of Prince Georges County knew something horrible was happening.
"I have daughters who are driving now and I'm afraid for them," said one neighbor. "I tell them to lock their doors when they get in the cars. I don't want them walking alone at nighttime."
Authorities suspect that Scott also killed Vilma Artis Butler, who was found dead in her burning home in Bowie, Md., in June 2008. Some police worry that Scott might be responsible for other unsolved deaths in Washington, D.C., Texas and Florida, where he is also known to have frequented.
He has a degree in computer science at the University of Maryland and had worked at UPS. According to law enforcement sources, Scott may have used the company's database to help select victims. He lived close to the Dewitts in Upper Marlboro, Md.