NASHUA — When SP4 Thomas Nadeau died in South Vietnam in 1968, it would take 43 years until his family learned the truth behind his death.

That truth came in March as Thomas' mother, Jeanine Nadeau, was on an operating table facing the possibility of her own death.

“The real story,” said Gale Hillbery, Jeanine Nadeau's daughter and Thomas Nadeau's sister, “was one of the other soldiers there picked up his gun that he said he had just cleaned, pointed it at my brother, pulled the trigger and said, 'Gotcha.' And the gun discharged.”

Jeanine Nadeau, 84, had heard several different stories over the years, from vague claims of friendly fire to the notion that he was an intelligence officer done in by the military. On another occasion in Nashua, when a monument was erected to fallen soldiers including “Tommy,” Jeanine Nadeau said a general and a major approached her and told her to “leave it alone.”

Something wasn't right.

The true story — at least the one that would finally give Jeanine Nadeau peace — came from Bill Sartell, a Pepperell, Mass., man who was Thomas Nadeau's best friend in Vietnam.

Earlier this year, Hillbery's husband happened upon a Vietnam veteran in Las Vegas who said the name “Thomas Nadeau”sounded familiar.

Jeanine Nadeau described the account as it was explained to her.

“He says, 'What's the name of your brother-in-law?' (My son-in-law) says, 'Thomas Nadeau.' He says, 'That rings a bell. You know, there's a friend of mine who's been trying for 43 years to get a hold of the Nadeau family.'”

The man instructed them to visit thewall-usa.com, a site which lists soldiers killed in Vietnam and allows users to leave messages. Under Thomas Nadeau, Hillbery found a note left by a Bill Sartell, which had been written five years before. The message is still there today.

“I would love to hear from any of Tom's family,” it reads. “I have tried several times to locate someone from his family. If you see this please e-mail me.”

Hillbery said that since five years had passed, she wondered if the email address provided was still good. But she wrote to Sartell anyway.

In March, she heard back.

“I got up at 4 a.m. Nevada time because Mum was in surgery for cancer, and I wanted to be up when the doctor called me,” Hillbery said. “And when I turned Facebook on, I had a friend request from Bill Sartell, and we spoke online for four hours.”

Jeanine Nadeau said that while she was undergoing surgery, the doctors thought she wouldn't make it. They called her daughter and told her to come and see her mother.

“And I came out of it, which you can't believe,” Nadeau said with a grin. She attributes her recovery to her daughter having contacted Sartell.

Sartell said he had never spoken of the war until talking with Thomas Nadeau's sister, Gale. The recollections were too traumatic.

“A long silence has finally been taken care of,” said Sartell in a telephone interview from Oklahoma, where he lives now.

Asked why he spent 43 years trying to get in touch with Hillbery, Sartell said: “She deserved to know what her brother went through in his last part of his life, and what his emotions might have been, because once you've been through this experience, you change. Your innocence is taken away from you.”

He also wanted to tell the Nadeau family what attributes Thomas had shown.

“Tommy was a straight shooter,” he said. “Tommy was friendly. Tommy was a helper. He was a caretaker. He watched out for everybody around him. He was a friend, he was intelligent, he was someone you would go to if you needed a mind or a brain.”

Sartell said that during Nadeau's last days, he was experiencing the things all soldiers go through at war. “We go through the uncertainty. We go through living the constant question: Will tomorrow come? But it just don't matter because today's today and tomorrow just don't matter.”

Now that she knows the true story, Jeanine Nadeau has peace. She also thinks Sartell has peace. She even has compassion for the man who killed her son.

“I can just imagine how (he) must feel,” she said. “He's still living, the guy who did it, God bless him, he's still living. And he must go through this an awful lot.”