Ronald DeFeo Jr leaves Suffolk County district court after a hearing, on New York's Long Island in 1974. Photo / AP

The man convicted of slaughtering his parents and four siblings in a home that later inspired the The Amityville Horror book and movies has died, prison officials said Monday.

Ronald DeFeo, 69, died Friday at Albany Medical Centre, where he was taken February 2 from a prison in New York's Catskill Mountains, the state Department of Corrections and Community Services said. The cause of his death wasn't immediately known.

DeFeo was serving a sentence of 25 years to life in the 1974 killings in Amityville, on suburban Long Island.

DeFeo, who was 23 at the time of his crimes, used a .35-calibre Marlin lever-action rifle to slaughter the family, who were found lying face-down in their beds on November 13, 1974.

Father Ronald DeFeo Sr, 43, and mother Louise DeFeo, 43, were both shot twice. Siblings Dawn, 18, Allison, 13, Marc, 12, and John, 9, were each shot once.

The home became the basis of a horror-movie classic after another family briefly lived there about a year after the killings and claimed the house was haunted.

George and Kathy Lutz purchased the house, but left 28 days later after reporting paranormal activity. They said there were "strange sounds, voices and green slime oozing from the walls," real estate site 6sqft reported.

A book and two movies — the 1979 original, starring James Brolin, Margot Kidder and Rod Steiger, and a 2005 remake — portrayed a home with strange voices, walls that oozed slime, furniture that moved on its own, and other supernatural features.

George Lutz told ABC News in 2006 that some of the reported events such as the green slime were embellished, while insisting the book and movie were based on events that truly happened during the family's 28-day stay.

The day before moving in they asked a priest to bless the home. Father Ray Pecoraro said he felt an unseen hand slap him and heard a voice say, "Get out". Then Pecoraro became ill with flu-like symptoms and his hands began to bleed, Lutz said.

The family still moved in, but within days they noticed strange occurrences including "odours in the house that came and went", Lutz told ABC.

"There were sounds. The front door would slam shut in the middle of the night," Lutz said. "I couldn't get warm in the house for many days."

The family kept the fireplace burning constantly in a futile attempt to stay warm, while also finding gelatinous drops on the carpet when they woke in the morning, he said.

Lutz said that at times his wife was physically transformed into an old woman with the face, hair and wrinkles of a 90-year-old.

Lutz claimed he woke at 3.15am almost every day, which was about the same time the DeFeo murders are believed to have happened.

One night he heard his children's beds "slamming up and down on the floor" above him but he was unable to act because he was immobilised in bed by an unseen force. Later he woke to see his wife levitating and moving across the bed, Lutz said.

The next morning they fled the home, leaving their possessions behind.

Months later, a group of psychic researchers spent a night in the house to investigate Lutz's claims. Researcher Lorraine Warren remembers an "overwhelming feeling" of "horrible depression" in the house, while the team said one of its photographs showed "what appeared to be a little boy, peering out from one of the bedrooms".

DeFeo had pursued an insanity defence at his trial, saying he heard voices that drove him to kill his family.

He unsuccessfully sought a retrial in 1992, claiming that his 18-year-old sister killed the other five family members and that he then shot her.

"I loved my family very much," he said at a 1999 parole hearing, where he also said he had gotten married while in prison.

The corrections department said it couldn't disclose why DeFeo was hospitalised, citing health privacy laws. The Albany County Coroner's Office, tasked with determining what caused his death, said it doesn't release such information, except to relatives of the dead.

- additional reporting Daily Mail