Two highly decorated former police detectives led double lives of heinous betrayal and corruption for decades, selling information to one of New York's most dangerous crime families and abetting no fewer than eight grizzly underworld murders, prosecutors told a packed courtroom in Brooklyn yesterday.

The allegations came in the opening statements of the long-awaited trial of Louis Eppolito, 57, and Stephen Caracappa, 64, who were arrested last March.

Already being billed as the most sensational police corruption case to be heard in the city for years, four books about it are in the works and rights have been sold for at least one Hollywood film - and that's even before the verdicts are in.

"The two men were not traditional mobsters," Mitra Hormozi, the New York prosecutor, told the jury. "They were better. They could get away with murder because these two men were New York City police detectives." Defence lawyers were expected to make their own statements later yesterday.

Ms Hormozi said that for a monthly stipend of $4,000 (£2,300), the men used their positions in the department to protect the Lucchese Mafia clan by selling it inside information about prospective police stings and investigations, and, more importantly, arranging the murders.

"Eppolito and Caracappa together were a perfect combination to gather and get information about the Mafia," she said.

The cases against both men are replete with dark ironies. Mr Caracappa helped create the department now dedicated to fighting mafia crime. Mr Eppolito, meanwhile, admitted late in his career that his father and grandfather were members of the Gambino crime family. He has even written an autobiography: Mafia Cop: The Story of an Honest Cop Whose Family Was the Mob.

Both men had retired to Las Vegas where they were arrested last year. Freed later, on bail of $5m each, they have come to trial insisting they are innocent.

The murders, prosecutors say, were committed at the bidding of Anthony "Gaspipe" Casso, a Lucchese family underboss currently serving a life sentence.

Allegedly, Casso paid them $75,000 for one hit and took to calling the pair his "crystal ball". Jurors will be told how they kidnapped one victim and delivered him personally to Casso for assassination. Another time they allegedly killed a mobster after pulling him over in their marked police car. They are also accused of giving the address of a victim tagged for assassination only to find the wrong man was killed.