Is killer's life story best left untold?

While he sat in his 12-by-7-foot cell on death row, Gary Lee Sampson has had time to gain 50 pounds and take 30 off. Time to watch his red hair go gray. And time to reflect on a bloody week in which he killed three men in cold blood.

And now, fours years after the murders, Sampson wants people to know what he's been thinking.

For the past 11 months, he has been working with a writer and evangelical minister on his biography. The working title: ''The DNA of a Killer: Society's Child, Gary Lee Sampson." The book, said biographer Deborah Murphy, is a cautionary tale that both she and Sampson hope will save others from following the same path by describing the warning signs of mental illness, and drug and alcohol abuse.

''Gary wants a book written before he gets executed because he wants to tell his story, his side, the true version of everything that happened," said Murphy, who first met Sampson 26 years ago when the two were growing up on the South Shore. ''He noticed certain signs of depression that led to alcohol and drugs and that's how you get into big trouble. He hopes telling his story can help young people. . . . He's trying to spare lives."

Relatives of Sampson's victims don't buy that story line.

''The idea that Gary Sampson wants to help other children makes me nauseous," said Mary Rizzo, mother of Jonathan Rizzo, one of Sampson's victims. ''If someone wants to write a book to help children they should write about Jonathan and Philip and Robert, they all led good lives."

In July 2001, Sampson carjacked Philip McCloskey, 69, of Taunton, and stabbed him to death. A few days later, he did the same to Rizzo, a 19-year-old college sophomore from Kingston. Four days after that, he strangled Robert Whitney, 58, of Penacook, N.H.

Sampson, who is from Abington, was tried in federal court and found guilty of the murders; he became the first person in Massachusetts sentenced to die under the federal death penalty. He is on death row at the Federal Correctional Institution in Terre Haute, Ind., where he is confined to his cell 23 hours day, said Trey Adams, a spokesman for the prison complex.

Sampson's case is notable for its brutality, but also for his short-circuited attempt to turn himself in the day before his killing rampage began. Telephone records confirmed that Sampson called the FBI from a pay phone that day; a fugitive facing charges in North Carolina, Sampson said he was trying to surrender. But the call was accidentally disconnected by an FBI clerk, and no action was taken. After the murders, Sampson surrendered in Vermont and confessed.

Those two facts -- the call to the FBI and his surrender -- were raised at the trial, but did not convince jurors that he should be spared from capital punishment.

Nor do they generate sympathy in the McCloskey family.

Scott McCloskey, son of Philip McCloskey, shares Mary Rizzo's distaste for Sampson's book venture. ''A biography about a murderer, that's usually the case, right?" he said. The killer ''goes out and kills and they find him and they do movies about him, they put these guys on a pedestal."

In a rambling, three-page typed letter laden with spelling errors, Sampson said he is deeply remorseful for the murders. ''At times the anguish is overwhelming," he wrote in the letter, mailed in response to a query from The Boston Globe.

Still, Sampson has told Murphy that he hopes the death penalty will be overturned. In the letter, he questions the social prudence of state-sanctioned execution, and cites Henry Ford's arguments against it. He also writes that although surrounded by ''abject drudgery," he is finding ''comfort and faith" in ''God and the religious instruction I am receiving.

''In my actions and in my deeds I strive to show remorse."

Murphy, who grew up in Rockland not far from Sampson, is also outspoken against the death penalty. ''Jesus said turn the other cheek," she said. ''And my own personal, emotional feeling is two wrongs don't make a right."

Murphy and Sampson first met briefly at house party in 1979. They did not keep in touch. Two years later she was paralyzed in a car accident, and several years after that she became a born-again Christian and later an evangelical minister. In 1989 she published a memoir, ''Tho I Walkest Through the Fire."

Murphy, 48, lives in Tampa and serves as a minister through a church called New Beginnings. She began corresponding with Sampson in August 2004, and signed an agreement to write his biography last November.

To facilitate the process, Murphy's husband, a general contractor, bought and refurbished a house near the Terre Haute prison. Murphy has been staying there, interviewing Sampson four times a month for several hours at a time, she said.

Because of the Son of Sam law that prohibits convicted murderers from profiting from their crimes, Sampson will not be entitled to any proceeds from the book. Murphy said she has not started shopping for a publisher.

She describes Sampson, who recently turned 46, as charismatic, creative, and remorseful. ''He has had nightmares about the crimes," she said. ''He has a conscience."

But Murphy also said she understands the pain a biography could cause the family members of Sampson's victims. Tragedy in her own life helps qualify her to write the book, she said.

In the same car accident that left her paralyzed, Murphy's brother was killed. Thirteen years earlier, in a hit-and-run in Boston that was never solved, Murphy's sister was killed. And in 2000 Murphy's niece was shot to death in Arizona and left on the street. That case has never been solved.

''I can understand how they feel," Murphy said, referring to the grieving relatives. ''But I am giving them a chance to know why, and that's something my family would certainly like to have."

In his letter to the Globe, Sampson is opaque about what motivated his murder spree. He writes ''many of the 'why questions' weigh excruciatingly heavy and our [sic] indelible upon my soul and have to [sic] earthly obtainable answers." A followup request for further details went unanswered.

Despite Sampson's professed discomfort, Murphy said, he has adjusted well to prison life. His arrest record dates back more than 25 years; before his conviction on the murder charges, he had served eight years for robbing banks. Still, Sampson has complained about the quality of the health care and the food, Murphy said.

The guards consider Sampson a ''neat freak" who immediately paints his cell every time he is transferred into a new one. Recently he was moved into a brand new facility ''which he is thrilled about," Murphy said. He spends most of his time in his cell watching nature shows on a 12-inch black and white television.

His cell is painted gray, lighted by a single fluorescent bulb, and equipped with a toilet, shower, writing table, sink, and bed. A single 6-inch-wide window looks out onto the prison grounds, said prison spokesman Adams.

Sampson has received dozens of letters of support from around the country, as well as a handful of romantic inquiries and a few cash gifts, Murphy said.

David Ruhnke, Sampson's lawyer, said ''there will be numerous grounds presented on appeal," but declined to elaborate what they will be.

Murphy, meanwhile, expresses hope that the book may sway the families of the victims to forgive Sampson and perhaps even speak out against his execution.

Scott McCloskey said that day will never come.

''I will never forgive him," McCloskey said.

''As far as I'm concerned, Gary Sampson is an evil man. And as far as the death penalty goes, he deserves it and I will be there when it happens."

Douglas Belkin can be reached at dbelkin@globe.com.