DALLAS — Authorities in Louisiana say they've closed two longstanding murder investigations because of confessions by a man being held in Texas who says he killed as many as 90 people over four decades.

An internal Louisiana State Police memo obtained by The Associated Press says 78-year-old Samuel Little provided details on two killings in the Gulf Coast town of Houma "that only the murderer would have known."

Fifty-nine-year-old Dorothy Richard was found dead in 1982 and the body of 40-year-old Daisy McGuire was discovered in 1996. Both had been strangled.

The memo says Little has confessed to other killings in Louisiana and those claims are being investigated.

Little is being held on a murder charge in West Texas .

He was already serving a life sentence in California when he was interviewed by a Texas investigator that resulted in the confessions.