A grand jury indicted a 73-year-old man on Thursday for the alleged murder of his first wife more than 50 years ago who he had insisted accidentally drowned while fishing.

The suspect in this Louisiana case, Felix Vail, is a mysterious figure who's been under scrutiny for other possible crimes. He had a girlfriend who disappeared in 1973 and a second wife who hasn't been seen since 1984.

Investigative journalist Jerry Mitchell of the Jackson Clarion Ledger, who's written a series of articles and a book about Vail, said "his is the oldest possible serial killer case in U.S. history."

Mary Horton Vail died on Oct. 28, 1962. Her husband said she fell overboard into the Calcasieu River, near Lake Charles, La. and authorities deemed it an accident at the time, KATC said.

But Vail had taken out a life insurance policy on his wife two months earlier and the autopsy contained details undermining his assertion that she fell. There was a 4-inch bruise on the back of her neck and a scarf was shoved 4 inches into her mouth.

Mitchell's reporting spotlights other inconsistencies in Vail's version of events.

Calcasieu Parish Coroner Dr. Terry Welke revised the decades-old determination and said she died before her body hit the water. The Calcasieu Parish District Attorney John DeRosier charged Vail with second-degree murder, which would lead to a life sentence if convicted.

“All we wanted from the beginning was justice, and now we feel we’re getting justice,” said Will Horton, Mary's brother. “We’re going through due process that we should have gone through 51 years ago.”

After Mary's death, his girlfriend Sharon Hensley disappeared in 1973. Vail told her family that he saw her for the last time in Key West boarding a boat with an Australian couple for a trip around the world, KPLC said.

Vail concocted a similar story to the mother of his second wife Annette Craver. Vail was 40 when he met Craver in the early 1980s and she was 15. Her mother Mary Rose claimed that Vail took control of $100,000 that her daughter inherited when her father died and coerced her into signing over the deed to a home in Tulsa, Okla.

Vail told authorities he saw Craver for the last time in September 1984 when she boarded a bus for Mexico, but Craver's family said the couple was together at least a month after that.

A hearing on Aug. 14 will decide if Vail is eligible for a public defender, the Sulphur Daily News said.