The FBI has confirmed that a senior citizen who has murdered at least 50 people is the most prolific serial killer in US history – and the law enforcement agency is turning to the public for help identifying more victims.

Samuel Little, 79, has confessed to killing 93 victims – mostly women — between 1970 and 2005, the FBI said Sunday.

Investigators have confirmed Little’s involvement in 50 homicides, and FBI crime analysts believe all of his confessions are credible.

Many of his victims’ deaths were initially ruled overdoses or attributed to accidental or undetermined causes, and some bodies were never found, the FBI said.

“For many years, Samuel Little believed he would not be caught because he thought no one was accounting for his victims,” said FBI crime analyst Christie Palazzolo.

Little, a former boxer also known as Samuel McDowell who has drawn several eerie portraits of his purported victims, was jailed for life in 2014 after being convicted of three murders.

Those three victims, all women, were beaten and strangled.

“Even though he is already in prison, the FBI believes it is important to seek justice for each victim — to close every case possible,” Palazzolo said.

The FBI has set up a website showing Little’s sketches, his videotaped confessions and information about five unconfirmed cases “in hopes that someone may remember a detail that could further the investigation.”

Those unconfirmed murders allegedly happened in Miami, Florida; North Little Rock, Arkansas; Covington Kentucky; Las Vegas, Nevada; and New Orleans, Louisiana.

With Post wires