CHARLOTTE, N.C. — Authorities said Tuesday they will re-examine the shooting death of a man in the Florida Keys more than four decades ago, after learning he was the third of five husbands to a serial widow charged in one of their deaths.

‘‘We’re absolutely going to look into this,’’ Monroe County, Fla., Sheriff’s Lt. Nancy Alvarez told The Associated Press on Tuesday. ‘‘Anytime you get someone that might be a black widow or that might have that in their background, you always want to look at the possibilities. We want to make sure she wasn’t involved in his death.’’

Southern Ohio native Betty Neumar, now 76, was charged last month in North Carolina with solicitation of murder in the July 1986 death of her fourth husband, Harold Gentry.

Investigators in Stanly County, Gentry’s home, are urging authorities elsewhere to investigate deaths of the other husbands, including two who died in Ohio and one who died of an infection that could indicate he was poisoned.

In the Florida case, Richard Sills was found dead in his apartment in 1965, and wife Betty told police they were arguing when he pulled out a gun and shot himself in the head. Authorities quickly closed the case, saying he died from a self-inflicted gunshot wound.

Alvarez said Florida investigators planned to look at medical records and other evidence to see how Sills’ case was handled. ‘‘It’s going to be a timely process, but we’re on it,’’ she said.

Neumar, who lives in Augusta, Ga., is being held on $500,000 bond in the Stanly County jail. A telephone message left for her attorney, Charles Parnell, was not returned Tuesday. Her daughter with Harold Gentry, who also lives in Augusta, has declined to comment.

Not much is known about Neumar’s relationship with Sills or her first two husbands, who died in Ohio, investigators say.

But some details of her early life are beginning to emerge. The AP found records showing she was born in 1931 in Ironton, and graduated high school in South Point in the late 1940s. Her first husband was Clarence Malone, who died in 1952.

Her second husband, James Flynn, who was born in New York, died two years later. She had two children from those early marriages, but a son died in 1985.

At some point, Neumar moved to Jacksonville, Fla., where she began cutting hair, according to Florida records. On her cosmetology license from 1961, she used the name Betty Flynn. She worked in beauty shops in the early 1960s. In 1964, she married Sills and moved into an apartment in Big Coppitt outside of Key West.

After Sills’ death, Neumar met Gentry in Florida. The couple married in the late 1960s in Georgia, and after he retired from the Army, they moved to the town of Norwood, about an hour east of Charlotte.

Gentry was found shot to death inside the couple’s home on July 14, 1986. Three years later, she married her fifth husband, John Neumar. He died in October, and authorities in Augusta, Ga., are investigating whether his death — officially listed as sepsis, bacterial infection of the body’s blood and tissues — might have another cause, such as arsenic poisoning.

Harold Gentry’s brother had begged investigators for two decades to take another look at the case, but his requests were ignored. It was finally reopened last year after Al Gentry asked newly elected Sheriff Rick Burris to look into it.

Former Police Officer Donnie Mullis has told the AP that an informant talked to him a few weeks before Gentry was killed, saying then-Betty Gentry offered him money to do the job. Mullis said he passed along the information to his two superiors, but they ignored the tip.

Stanly County Sheriff’s Detective Scott Williams has said his office is looking into why no one took the informant’s tip seriously.

The AP News Research Center in New York contributed to this report.