Samuel Little, one of most notorious U.S. serial killers, dead at 80

Dec. 31 (UPI) -- Samuel Little, the man regarded by many in law enforcement as the deadliest serial killer in U.S. history, has died at a California hospital at the age of 80.

Little, who confessed to at least 93 murders nationwide, had been serving three consecutive life sentences when he died early Wednesday at a hospital outside the prison system, the California Department of Corrections and Rehabilitation said.

The cause of Little's death will soon be determined by the Los Angeles County medical examiner.

Little was convicted in 2014 for the murders of three women in the late 1980s -- Carol Alford, 41, in 1987 and Audrey Nelson, 35, and Guadalupe Apodaca, 46, in 1989.

He was linked to the deaths by forensic DNA evidence and arrested in Kentucky in 2013.

Authorities believe that Little's claims that he killed almost 100 people are credible. The FBI says his staggering victim count makes Little the most deadly serial killer in U.S. history.

Investigators have so far verified 50 of his admitted victims, and many others are pending final confirmation.

After his apprehension, Little confessed to strangling his victims, who were all women, between 1970 and 2005. Many of the deaths were originally ruled overdoses or attributed to accidental or undetermined causes.

Authorities say he preyed on marginalized and vulnerable women who were often involved in prostitution and addicted to drugs. For years, many of the bodies went unidentified and the women's deaths uninvestigated.

Little was also charged with killing women in Mississippi and Florida in the early 1980s, but was not indicted by Mississippi prosecutors and was acquitted by a Florida jury. He had earlier served time for assaulting a woman in Missouri and attacking and holding another woman in San Diego against her will, the FBI said.