(NBC News) – A serial killer who has faced 90 murders has attracted 16 of his alleged victims as the FBI works to bring him to decades-old cold cases across the country.
Samuel Little was convicted in 2014 of killing three women in California in 1987 and 1989. He was sentenced to three consecutive life sentences.
He had always maintained his innocence in these three cases, but last year against a jail transfer, the FBI said, "Little wanted to talk."
The 78-year-old said he killed 90 women and that between 1970 and 2005, the FBI attempted to line up those with unexplained deaths in more than a dozen states.
Recently, Little drew sketches of 15 women he allegedly killed. One of the victims he outlined was identified as a man killed in Miami, which is called "Mary Ann" or "Marianne" according to the FBI.
Shortly after Little's confessions in November, the FBI quickly confirmed that he had killed 34 people. Recently, eight more of his confessions have been confirmed or have reached open cases, the FBI said.
More than half of the confessions remain unconfirmed.
"Little has chosen to kill marginalized and vulnerable women who were often involved in prostitution and drug addicts. Their bodies were sometimes not identified and their deaths were not investigated, "the FBI said earlier.
Because Little, once a competitive boxer, usually threw his victims out of the race, there were no obvious signs that the victims had been killed.
Another challenge for the investigators is that Little can describe his victims and how and where he killed them in detail.
"The insecure timeline of Little has led to a verification challenge … along with the problems posed by the victims – Little, his methods, and how he moved – characteristics of his crimes that begin to explain, as he had for decades copying the murder, "said an FBI statement.
Little pleaded guilty to strangulation by Denise Christie Brothers in Texas in December.
He is "in poor health and is likely to remain in jail until his death in Texas," the FBI said in November. Their goal is "to identify their victims and, in unexplained cases, to ensure closure and justice."
But local officials in the places where Little has murdered his victims have a choice to file charges against him, an FBI spokesman said.