BELFAST, Northern Ireland — A Protestant militant who had been linked to one of Northern Ireland's most notorious murders was shot to death outside his home Wednesday morning, police said.

William Stobie, 51, was shot several times from close range as he walked up to his car in north Belfast, police said. Stobie reportedly had been warned that members of the outlawed Ulster Defense Association — to which he once belonged — intended to kill him.

An outlawed group called the Red Hand Defenders claimed responsibility for the killing, but police and analysts said the group was a cover name for members of the UDA, Northern Ireland's largest armed Protestant group.

Detective Superintendent John Brannigan said police had received a tip-off that UDA members intended to kill Stobie and warned him of the threat earlier this month. And Ed Moloney, a Belfast journalist who had earned Stobie's trust, said he talked to Stobie about the danger last week.

But human rights activists and Sinn Fein, the Irish Republican Army-linked party, asked that Northern Ireland's police be shut out of investigating Stobie's killing, arguing that they might be involved.

Sinn Fein spokesman Gerry Kelly said the predominantly Protestant police force "had most to gain" from Stobie's demise. He accused police of "getting rid of an embarrassment and a potential problem down the road."

Stobie had admitted once being a police double agent while he was in the ranks of the UDA, passing on intelligence about impending UDA attacks.

Last month state prosecutors dropped two murder charges against Stobie, including for the 1989 slaying of Catholic defense attorney Pat Finucane, one of the most high-profile unsolved murders in Northern Ireland.

Britain has been pursuing a special investigation into Finucane's murder because of Catholic claims that British security forces, particularly the anti-terrorist detectives who worked with Stobie, had been involved in targeting Finucane, who represented many suspected Irish Republican Army members.

In the UDA, Stobie was a "quartermaster" responsible for supplying firearms for attacks on Catholics.

He testified in court that he had supplied the weapons used to kill Finucane, who was fatally shot in his home in front of his wife and children at the dinner table. However, he insisted he hadn't known who the target would be when he supplied the weapons, and passed on a general warning to the police that a UDA gun attack somewhere was imminent.

The murder case collapsed after the key witness against Stobie — a former journalist who had claimed Stobie told him in 1991 that he had known Finucane was the target — suffered a nervous breakdown and could not testify.

Police armored vehicles on Wednesday sealed off Forthriver Road, the working-class Protestant district where Stobie's blanketed body remained lying on the pavement awaiting inspection by forensics experts.