DR JESSE Marcel Jr, who said he handled debris from the 1947 crash of an unidentified flying object near Roswell, New Mexico, has died at the age of 76.

Denice Marcel said her father was found dead at his home in Helena on Saturday, less than two months after making his last trip to Roswell. He had been reading a book about UFOs.

Over the past 35 years, Marcel Jr appeared on TV shows, documentaries and radio shows; was interviewed for magazine articles and books, and traveled the world lecturing about his experiences in Roswell.

"He was credible. He wasn't lying. He never embellished - only told what he saw,'' his wife Linda said.

Marcel's father was an Air Force intelligence officer and reportedly the first military officer to investigate the wreckage in early July 1947. Marcel Jr said he was 10 when his father brought home some of the debris, woke him up in the middle of the night and said the boy needed to look at it because it was something he would never see again.

His father maintained the debris "was not of this Earth,'' Linda Marcel said. "They looked through the pieces, tried to make sense of it.''

The item that Marcel Jr said fascinated him the most was a small beam with some sort of purple-hued hieroglyphics on it, she said.

After an initial report that a flying saucer had been recovered on a ranch near Roswell, the military issued a statement saying the debris was from a weather balloon.

"They were told to keep it quiet and they did for years and years and years,'' Linda Marcel said. Interest in the case was revived, however, when physicist and UFO researcher Stanton Friedman spoke with Jesse Marcel Sr in the late 1970s.

Mr Friedman wrote the forward to Marcel Jr''s 2007 book The Roswell Legacy, and described him as a courageous man who "set a standard for honesty and decency and telling the truth.''

"His legacy is that he had the courage to speak out when he didn't have to about handling wreckage that his Dad brought home,'' Friedman said Tuesday. "He worked with artists to come up with what the symbols on the wreckage looked like. He didn't have to do that. He could have kept his mouth shut. A lot of people did.''

On his last trip to Roswell in early July, UFO researcher and Earth science professor Frank Kimbler arranged for Marcel to visit the debris site and his childhood home.

"I remember my dad did say that he loved the ride up to the site that day because he was able to discuss science with Frank,'' Denice Marcel said in an email to The Associated Press. "One thing about my Dad, he was always reading something on astronomy or some kind of scientific journal. He loved astronomy with a passion.''

Marcel Jr graduated from medical school at the Louisiana State University School of Medicine in 1961 and joined the US Navy in 1962. He retired after nine years but later joined the Montana Army National Guard and became a flight surgeon in 1981. He was called back to active duty in October 2004 and served as a flight surgeon in Iraq for just over a year. He reached the rank of colonel.

"I know that one of the things that Dad would love to say is, 'If we are the only ones here then there is an awful lot of wasted space out there,''' Denice Marcel said. "He wasn't the first one to say this, but he did believe it. He also believed that everyone needed to know the truth, and that the Roswell Incident was a real event and that it was time for the cover-up to stop.''

He is survived by his wife and eight children. Funeral services are pending.

