US investigators have so far confirmed that a 78-year-old drifter -- who could potentially be the most prolific serial killer in American history -- is responsible for more than 40 murders, authorities said Thursday.
Samuel Little has confessed to 90 murders committed between 1970 and 2005, targeting mainly drug addicts and prostitutes across the country, according to the Federal Bureau of Investigation (FBI).
Bobby Bland -- the district attorney in Ector County, Texas, where Little was being held on a murder charge -- announced Thursday that at least six more of his confessions have been verified over the last two weeks, bringing the total number of confirmed killings to more than 40.
"He's talking about things, cases that happened up to 50 years ago, and he's giving details on all these different murders, and none of the statements he's made have proven to be false," Bland told AFP.
His office also announced that Little had pleaded guilty to the 1994 murder of Denise Christie Brothers in Odessa -- the case that initially led to his extradition to Texas and spurred him to confess.
The FBI has been working with federal, state and local agencies to match Little's confessions to unsolved murders across the country.
The agency said in an earlier report that Little "remembers his victims and the killings in great detail."
If all 90 confessions are confirmed, Little would be the deadliest known US serial killer.
Little admitted to the Texas murder after Bland agreed to waive the death penalty in that case, a concession made "to gain his trust," the prosecutor told AFP.
The septuagenarian was to be transferred back to California, where he was already serving a life sentence for three murders.
The former boxer also known as Samuel McDowell was first arrested at a homeless shelter in Kentucky in 2012 and extradited to California to face drug charges.
Once there, DNA evidence linked him to three cold cases and he was convicted in 2014 of murdering three women in Los Angeles between 1987 and 1989.
All three had been beaten and strangled.