A 78-year-old inmate who says he killed about 90 people as he moved around the country for nearly four decades offered his confessions as a bargaining chip to be moved from a California prison, authorities say.

The FBI said in a statement Tuesday that Samuel Little offered the deal in exchange for being moved from California State Prison in Los Angeles County, but it didn't say why he requested the transfer, where he asked to go or whether his offer was accepted. It did say that Little, who is in poor health and relies on a wheelchair, will likely stay in jail until his death in Texas, where he was brought in September to face charges in the 1994 killing of a woman in Odessa.

Little was convicted in 2014 of killing three women in separate attacks in Los Angeles County in the 1980s, and prosecutors said during his trial that he was likely responsible for at least 40 killings since 1980. Authorities at the time were looking for possible links to deaths in Florida, Georgia, Kentucky, Louisiana, Mississippi, Missouri, Ohio and Texas.

A Texas Ranger, James Holland, traveled to California earlier this year to interview Little about the 1994 Odessa killing. That interview resulted in a series of confessions and near daily discussions "to create the most accurate accounting possible of Little's crimes," according to the FBI statement.

"Little remembers his victims and the killings in great detail," the FBI said. "He remembers where he was, and what car he was driving. He draws pictures of many of the women he killed. He is less reliable, however, when it comes to remembering dates."

Little, who also went by the name Samuel McDowell, targeted vulnerable women who were often involved in prostitution and addicted to drugs, authorities say. Once a competitive boxer, he usually stunned or knocked out his victims with powerful punches before he strangled them while masturbating.

"With no stab marks or bullet wounds, many of these deaths were not classified as homicides but attributed to drug overdoses, accidents, or natural causes," the FBI said.

Based on information Little has provided, authorities in several states have already confirmed his ties to 34 killings that happened between 1970 and 2005, not including the three he was convicted of in California. Investigators in Mississippi and South Carolina recently announced that they had closed cold cases based on Little's information. And police in Maryland and other states are looking into whether it can help them solve their own unsolved killings, including the 1973 strangulation in Omaha, Nebraska, of Agatha White Buffalo , whose body was found upside-down in a 55-gallon drum.

"He went through city and state and gave Ranger Holland the number of people he killed in each place," said Christina Palazzolo, an FBI crime analyst who collaborated with Holland. "Jackson, Mississippi — one; Cincinnati, Ohio — one; Phoenix, Arizona — three; Las Vegas, Nevada — one."

Palazzolo said Little lived a nomadic life from the time he dropped out of high school and left his Ohio home in the late 1950s. He would shoplift and steal to gather the money to buy alcohol and drugs, but he never stayed in one place for long, she said.

Enzo Yaksic, co-director of Northeastern University's Atypical Homicide Research Group, said Little's wandering lifestyle appears to set him apart from the habits of American serial killers such as Gary Ridgway, the so-called Green River Killer.

"Little is unique in that modern day serial murderers rarely travel the distances he claims to have traversed and instead select vulnerable victims from their own communities," Yaksic said. "This behavior, paired with his selection of vulnerable people, no doubt contributed to his longevity. Most serial killers in today's society kill two or three victims and are caught within a few years."

Ridgway, who is serving a life sentence, pleaded guilty to killing 49 women and girls, making him the most prolific serial killer in U.S. history in terms of confirmed kills, though he has said he likely killed more than 71. Ted Bundy confessed to 30 homicides from about 1974 to 1978 and John Wayne Gacy killed at least 33 young men and boys in the 1970s. Both of them were executed.

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