Felix Vail was was found guilty of the 1962 murder of Mary Horton Vail, and two other women connected to him have mysteriously disappeared

America's Oldest Serial Killer? Mississippi Man, 77, Convicted of Wife's Death Is Tied to Disappearance of Two Other Women

Almost from the day her husband, Felix Vail, reported that his wife fell overboard and drowned 54 years ago – during a nighttime trotline fishing trip on the Calcasieu River near their home in Lake Charles, Louisiana – Mary Horton Vail’s family was suspicious.

“I never believed it was an accident,” her younger brother Will tells PEOPLE in this week’s issue, on newsstands now.

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Lending more mystery were the bruises on Mary’s head and neck, a scarf in her mouth and a double-indemnity insurance policy that Felix recently had taken out on the 22-year-old mother of the couple’s 3-month-old son. But although Felix, now 77, was questioned, authorities at the time ruled the death an accident.

He returned with his son, Bill, to his hometown of Montpelier, Mississippi, then grew itinerant as he drifted through jobs and women, two more of whom later disappeared – Sharon Hensley in 1973, and another he married, Annette Craver, in 1984 – after last being seen with him.

To read more about the mysteries surrounding Felix Vail, pick up this week’s issue of PEOPLE, on newsstands now.

All three women’s families thought Vail a possible killer. But not until they were united and learned about each other’s losses, and a possible pattern emerged, did they believe Vail might be caught.

Indeed, alerted by the work of Jackson, Mississippi, Clarion-Ledger/USA Today investigative reporter Jerry Mitchell – who jumped on the sleuthing begun by Craver’s mother, Mary Rose, and then dug deeper – prosecutors in Louisiana charged Vail in 2013 with Mary’s Oct. 28, 1962, murder.

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He pleaded not guilty, but jurors disagreed. Vail was convicted last month and faces life in prison when he is sentenced on Sept. 26.

The fates of Craver and Hensley, however, are still unknown.

Vail told the families of each woman that they left him on their own: Craver reportedly after boarding a bus to Mexico, and Hensley allegedly with an impromptu decision to join a mysterious couple’s sailing trip.

No more charges are pending against him.

But the facts of their disappearances followed by Vail’s questionable explanations were presented at trial, allowing prosecutors to portray Vail as perhaps the nation’s oldest serial killer.