The murder trial involving what experts say is the oldest serial killer suspect case in U.S. history is expected to start Aug. 17.

The murder trial involving what experts say is the oldest serial killer suspect case in U.S. history is expected to start Aug. 17.

Felix Vail, a 74-year-old native of Mississippi is charged with the murder of Mary Horton Vail, whose 1962 death in Lake Charles, Louisiana, was originally ruled an accidental drowning.

He is the last known person to be with her and two other women: his common-law wife, Sharon Hensley, who disappeared in 1973; and his wife, Annette, who disappeared in 1984.

The Louisiana Appeals Court has ruled the disappearances of those women should be allowed as evidence under state law. The Louisiana Supreme Court is now considering an appeal.

Vail has insisted he is innocent, saying the charges against him are "fabricated" and that "there is a large amount of money, hate and political ambition behind them."

Louisiana authorities reopened the case after The Clarion-Ledger published its 2012 story "Gone," in which a pathologist pointed to a bruise on the back of Mary Vail's head and a scarf 4 inches in her mouth as proof of homicide.

The coroner in Lake Charles, who is also a forensic pathologist, has since ruled her death a homicide.

In late 2013, The Clarion-Ledger interviewed Jacine Brooks of Sulphur, Louisiana, who worked in 1962 in the Traveler's Insurance Claim Department in Lake Charles.

She said Vail's wife never signed the life insurance policy he took out before she died on Oct. 28, 1962.

"She did not sign the policy, and she needed to sign it," Brooks said. "The agent got in a little trouble."

Vail did not take out a life insurance policy on himself, she said.

In a hearing Thursday, she testified that Vail was eventually paid a settlement.

Judge Robert Wyatt rejected the prosecution's request to introduce the testimony of an ex-wife of Vail who said he kept surgical saws in a secret compartment in his Volkswagen.

"I can see it just like it was yesterday," she told authorities. "In that vehicle, there were sinister, surgical looking saws of all shapes and sizes in a neat, neat formation."