Samuel Little drew their portraits in paint and in pencil, filling out the contours of the faces of women he said he killed over nearly four decades.

He recalled the color of their eyes and the way they wore their hair, or locations crucial to their murder. One portrait simply says, “Tall girl by highway sign” in Cincinnati, “1984 or 74.”

Little, 79, in failing health and already serving three consecutive life sentences in California for killing three women, has confessed to dozens of murders across the United States.

His details and confessions have so far proved true, prosecutors have said, leading authorities to a grim conclusion: With more than 60 killings linked to him, Little may be the most prolific serial killer in American history.

Ohio prosecutors said Friday that information obtained from Little in prison, part of a stream of confessions extracted by a Texas Ranger, led to a grand jury indictment against Little in the 1981 slaying of Anna Stewart and another woman still unidentified.

“This is truly shocking. Little is likely responsible for committing more murders than anyone else in the United States,” Hamilton County Prosecutor Joseph T. Deters said.

Gary Ridgway, known as the Green River Killer, is thought to be the country’s deadliest serial killer in terms of guilty pleas, with 49 victims.

Little grew up in Ohio and is linked to at least five murders there, the Associated Press reported, part of a string of slayings between 1970 and 2005 he said he committed.

Little was arrested in a Kentucky homeless shelter in 2012 and extradited to California, where he was wanted on a drug charge, the FBI said. Then investigators found a DNA match to three women — all beaten and strangled. Other women testified in his 2014 trial that they narrowly escaped similar encounters with Little.

He remained defiant and maintained his innocence, though prosecutors believed he was responsible for far more deaths.

Little remained tight-lipped about other crimes until Texas Ranger James Holland visited Little in prison to discuss unsolved murder cases in Texas.

Infirm and without appeals, Little began to pour out confession after confession, Bobby Bland, the district attorney for Ector County, Tex., told the Associated Press, including the 1994 strangulation death of Denise Christie Brothers in Odessa.

There were others. A cascade of investigators from across the country traveled to California to corroborate their cold-case killings based on the information gushing from Little.

“At this point in his life, I think he’s determined to make sure that his victims are found,” Bland said. “Nothing has been proven to be false.”

So far, investigators have connected more than 60 deaths to Little, according to Bland, who credited Holland for gaining Little’s trust during the investigation. Holland determined the number of victims could be as high as 93, Bland said.

Little has painted and drawn portraits of several unknown women he said he killed, and the FBI has released them in hopes they will close long-open files.

Many of the victims were deliberately chosen because they were marginalized — sex workers and drug users whose deaths may have not drawn much police attention, the FBI said. Little would allegedly punch his victims and strangle them. Those deaths were often attributed to drug overdoses, accidents or natural causes, the FBI said.

But Little allegedly targeted women for other features.

“He specifically looked for girls with a certain neck type that he liked. … That’s how twisted this guy is,” Deters, the Ohio prosecutor, told reporters. He pointed out that Friday was Little’s birthday.

“You know the old saying, only the good die young?” Deters said. “This piece of garbage is 79 today.”

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