He visited the sheriff's office dozens of times and made just as many phone calls. When authorities finally listened, they wound up arresting the person Mr. Gentry had always suspected: his brother's now 76-year-old former wife, who was charged last month with hiring a hit man to gun him down.
"This is something I've been waiting for for a long time," Mr. Gentry said.
But Mr. Gentry's persistence might have led investigators to a far more chilling discovery about Betty Neumar. After arresting her, authorities realized that she had been married five times since the 1950s, and each union ended with the death of her husband.
Authorities say they've notified law enforcement where Ms. Neumar is believed to have lived with the men. No one has said whether the deaths are suspicious, but some officials are reopening the cold cases.
Mr. Gentry had been showing up for years at the sheriff's office and talking to anyone who would listen about the case. His brother's body, with several gunshot wounds, was found in the couple's home July 14, 1986.
Ms. Neumar, who was out of town the day her husband was killed, showed no emotion when she got back, Mr. Gentry said. When she pulled up to the house that was surrounded by flashing lights and filled with police officers, he recalled, she blurted out that she had been in Augusta the previous night -- before he even said a word.
"If she had gotten out of that car with tears in her eyes and asked me why would anybody kill Harold, I would never have suspected her at all," he said.
Harold Gentry met Ms. Neumar -- who was then Betty Sills -- in Florida and they married on Jan. 19, 1968, in Charlton County, Ga., when he was 29 and she was 36. The couple moved to Norwood, about an hour east of Charlotte, in the late 1970s after he retired from the Army after 21 years of service.
At first pleasant, she grew to become "cold" to his brother and family, Al Gentry said. By 1986, the marriage was strained and Harold Gentry was living in a camper in the front yard.
Al Gentry and his brother, Richard, said that after Harold Gentry was killed, Ms. Neumar collected at least $20,000 in life insurance plus other benefits from the military and sold the couple's house and other items. But as recently as a few years ago, bankruptcy records indicate, Ms. Neumar had no income other than a small monthly Social Security check -- but had more than three dozen credit cards and hundreds of thousands in debt. At a hearing earlier this month, prosecutors said she also had at least one overseas bank account.
After Mr. Gentry's death, Ms. Neumar remarried two more times. Once was to 79-year-old John Neumar, who died in October. Authorities in Ms. Neumar's hometown of Augusta are examining the death, and detectives went to her home two weeks ago and seized an urn with his ashes, said Richmond County sheriff's Lt. Scott Peebles.
His cause of death was listed as sepsis -- an illness caused by a bacterial infection of the body's blood and tissues -- and his body was cremated shortly after his death. Lt. Peebles said investigators would test the remains to see whether there "were any other factors that contributed to his death," including whether he was poisoned by arsenic, which can cause sepsis-like symptoms.
The couple were married for about 14 years. They filed for bankruptcy in April 2000, and records show they owed $206,300 on 43 credit cards. They listed $14,355 in assets and had a combined monthly income of about $1,800.
Ms. Neumar was charged with solicitation of murder and is being held on $500,000 bond. She does not yet have an attorney, and a message from The Associated Press given to a jailer went unanswered. Her daughter with Harold Gentry, who also lives in Augusta, declined to comment.