Authorities are investigating allegations that a former mob-busting FBI agent helped Colombo capo Gregory Scarpa carry out four Brooklyn murders during the years the gangster served as a top echelon informer for the agent, Gang Land has learned.

Two of the slayings – one committed by Scarpa, the other by an associate – took place after the FBI agent, R. Lindley DeVecchio, allegedly told the gangster that two Brooklyn hoodlums were stool pigeons just like him, sources said.

Mr. DeVecchio allegedly told Scarpa that mobster Joseph “Joe Brewster” DeDomenico had “found God” and was prepared to tell the truth if subpoenaed, and that Patrick Porco, a young drug dealing buddy of Scarpa’s son Joseph, was talking to police, sources said.

DeDomenico, 44, was shot to death on September 17, 1987. Porco, 18, was killed over the Memorial Day weekend in 1990.

Sources said the Brooklyn district attorney’s office also has evidence that Mr. DeVecchio, who has repeatedly denied any wrongdoing as an FBI agent, aided Scarpa in the murders of two rival hoodlums he shot to death during the bloody 1991-92 mob family war.

The victims, mob associate Larry Lampesi and capo Nicholas “Nicky Black” Grancio, members of a rival Colombo faction headed byVictor “Little Vic” Orena, were shot to death by Scarpa’s crew in 1992. Sources said Mr. DeVecchio facilitated Grancio’s murder by calling off a police surveillance team to allow Scarpa to kill him, and assisted Scarpa in Lampesi’s murder by letting him know where to find his target.

“The evidence is credible but it remains to be seen whether a murder case can be made,” a law enforcement source said, noting that the statute of limitations has long since passed on all other possible charges.

“Lin discussed the murders with Greg before they happened, and after they happened, and knew they were going to happen – that is the allegation,” a source who is familiar with the probe by the D.A.’s office said.

Just how far Mr. DeVecchio went in aiding his prized informant has been kicked around by federal prosecutors and mob defense lawyers for more than a decade. He was investigated by the Justice Department’s Office of Professional Integrity in 1997, but no charges were ever brought.

Accounts by Scarpa’s family detailing Mr. DeVecchio’s close, allegedly corrupt, working relationship with Scarpa reached Gang Land a decade ago. Those charges could never be confirmed and Mr. DeVecchio has strongly denied any wrongdoing.

The central figure in the new investigation, sources said, is Scarpa’s longtime lover, Linda Schiro, who hooked up with the then 36-year-old mobster in 1964 several months before her 19th birthday and raised two children with him. Their son, Joseph, was shot to death in a drug-related gang murder in 1995 at 24. Scarpa, who contracted the AIDS virus in a blood transfusion, died in prison a year earlier at 66. Ms. Schiro, now 60, met Mr. DeVecchio numerous times during visits to the gangster’s home, according to court documents.

While Ms. Schiro is the linchpin of the investigation, the allegations were delivered to the D.A.’s office by Angela Clemente, a private investigator who obtained much of her information from a woman with whom Ms. Schiro planned to write a book several years ago, sources said.

Sources said Ms. Clemente, who has investigated Mr. DeVecchio and other alleged government abuses for years, filed a report with the D.A.’s office last year after a federal judge refused to toss Little Vic Orena’s murder and racketeering conviction based on lesser allegations against the 65-year-old retired G-man.

Sources said the report is based largely on information Ms. Clemente obtained from Sandy Harmon, who had planned to pen the Schiro-Scarpa book, and that it contains allegations that have been knocked down by detectives and investigators for Brooklyn’s D.A., Charles Hynes.

One discredited charge is that Joseph Scarpa killed Porco, a lifelong friend whose bullet-riddled body was found on May 27, 1990, in the Sheepshead Bay section of Brooklyn, on orders from his father.

“Greg wanted him to, pushed him to do it, but the kid couldn’t do it,” a source said.

Prosecutors have confirmed the essence of the report, however, and plan to cajole or coerce Ms. Schiro to testify before a grand jury in the hope of lodging murder charges against Mr. DeVecchio and others, sources said.

Ms. Shiro, who implicated Mr. DeVecchio in two minor transgressions during an internal FBI probe – she said he accepted a plate of lasagna and a Cabbage Patch doll as gifts from her and Greg – declined to comment when contacted by Gang Land.

“These allegations are preposterous,” Mr. DeVecchio’s attorney, Douglas Grover, said. “There’s no way that such a well-respected, talented agent who enjoyed a great career with the FBI was ever going to get involved in something like this. There is no doubt that Scarpa was a murderous thug, but there is nothing to suggest that Lin participated in or condoned any of Scarpa’s conduct while he was a major FBI informant.”

Gang Land could not reach Ms. Clemente or Ms. Harmon.

Whether Mr. DeVecchio broke the law in his dealings with Scarpa is an open question. If he did, it wasn’t the first time a FBI agent committed crimes with the daredevil gangster-informer.

In fact, as reporter Tom Robbins and I disclosed in the Daily News in 1994, G-men broke several laws when they tapped the gangster to use his unique talents to find out where the Ku Klux Klan had buried the bodies of three civil rights workers they killed in sleepy town of Philadelphia, Miss. during the Freedom Summer of 1964.

His name never came up in the trial last year at which a former Klan leader, Edgar Ray Killen, was convicted of manslaughter, or at the 1967 federal trial that ended with seven Klansmen being found guilty of civil rights violations. But those prosecutions probably wouldn’t have happened if not for Scarpa’s efforts.

Under intense pressure from President Johnson to solve the case, FBI Director J. Edgar Hoover, whose agents had begun cultivating mob informers after state troopers rousted a 1957 meeting of top mobsters in Apalachin, N.Y., looked to the Mafia for help.

Scarpa, a fearless gangster then on the rise under another rising star, Joseph Colombo, was an obvious choice. Like most wiseguys, he fancied himself a patriot, and he was well groomed in the art of persuasion. He quickly agreed to help New York FBI agents who approached him.

“He was a cowboy. He was an action guy,” a former agent who had dealings with Scarpa in the 1960s said.

Scarpa flew to Miami and registered at the Fontainebleau Hotel to establish an alibi. He then flew to New Orleans and met agents who drove him to Philadelphia and pointed out a local merchant who likely knew where the bodies of the civil rights workers were buried.

Scarpa stopped at his store, said he was new in town, and put down a deposit on a television set. He promised to pick it up by closing time.

When he returned, he got the merchant to help him carry the TV to his car, slapped him over the head with a pipe, tied him up, and threw him in the trunk of the car. He drove to a prearranged location, a shanty deep among tall loblolly pines where FBI agents were hidden outside.

Inside, Scarpa tied the Klansman to a chair and demanded, “What happened to the three kids?”

After several queries proved fruitless, Scarpa went outside, asked one of the agents for his gun, and went back inside. He stuck the gun barrel into the Klansman’s mouth and said, “Tell me the f-ing truth or I’ll blow your f-ing brains out.”

The terrified merchant gave up the location of the graves and the names of culprits, which, the agents outside told Scarpa, rang true.

Scarpa went back into the shack, loosened the ropes, and cautioned the merchant to wait before finding his way home. In a final warning, he put the gun back into his mouth and said, “If we find out it’s not true, I’ll be back.”

Within 72 hours, some 44 days after James Chaney, Michael Schwerner, and Andrew Goodman disappeared, FBI agents, using draglines and a bulldozer, retrieved their decomposing bodies from an earthen dam under 17 feet of red Mississippi clay.