The death of a key witness will not stall the murder case against Kennedy nephew Michael Skakel.

Prosecutor Jonathan Benedict said he would still prosecute the case "without batting an eyelash," despite the death of witness Gregory Coleman.

Coleman, 39, was found dead Tuesday morning of an apparent drug overdose in the driveway of a home in Rochester, N.Y., police said.  

Benedict said he would submit for evidence a transcript of Coleman's testimony from pretrial hearings. 

Prosecutors had been expected to rely heavily on Coleman's testimony that Skakel admitted killing 15-year-old Martha Moxley in 1975. During a pretrial hearing, Coleman testified that Skakel once told him: "I'm gonna get away with murder. I'm a Kennedy." 

But Coleman also admitted during a hearing in April that he was under the influence of heroin when he testified. 

"It is a tragedy. He was an engaging individual," Benedict said. 

Moxley was beaten to death with a golf club that matched a set owned by the Skakels, who lived nearby in an exclusive Greenwich neighborhood. Skakel was also 15 at the time. 

No arrests were made in the Moxley case for more than 24 years after the killing. Skakel was charged in January 2000 and later arraigned as a juvenile because he had been a juvenile at the time of the killing. A judge ruled Skakel should be tried as an adult.

Skakel, 40, is the son of Rushton Skakel, the brother of Robert F. Kennedy's widow, Ethel. He has pleaded innocent to the charge. 

His lawyer, Michael Sherman, declined to comment on the possible effect of Coleman's death on the prosecution's case. 

"I'll let others make a judgment on this," he said. 

Dorthy Moxley, Martha's mother, said there are other witnesses — some of them only recently located — who can support Coleman's allegation that Skakel confessed. 

"I thought he was close to a hero for coming forward," Moxley said of Coleman. "I don't think it mattered if he was on drugs." 

Sherman said Skakel, who has had his own struggles with addiction, looks upon Coleman's death as "a very sad event." Coleman and Skakel were classmates at the Elan School in Poland Springs, Maine, in the late 1970s. 

During a hearing to determine if enough evidence existed to bring the case to trial, Sherman asked Coleman why he told the grand jury Skakel discussed the murder five or six times but later said it was only once or twice. 

"I was on drugs when I came before the grand jury," Coleman answered. 

Another former classmate, John Higgins, testified that Skakel told him of the killing during a tearful confession on the front porch of a dormitory while the two served as night guards. 

Higgins said he had previously lied to investigators when he said Skakel didn't know if he committed the murder. He also admitted asking about a $50,000 reward in the case. 

The Associated Press contributed to this report.