Attorneys for Michael Skakel (search) urged the Connecticut Supreme Court to throw out his murder conviction, arguing Friday that prosecutors waited too long to try the Kennedy cousin and failed to turn over crucial evidence.

Skakel, a nephew of Ethel Kennedy (search), was convicted in 2002 of bludgeoning his neighbor Martha Moxley (search) to death in 1975, when both were 15. Skakel, now 44, is serving 20 years to life in prison.

Skakel's lawyers argue that a statute of limitations at the time of the killing set a five-year limit for prosecution of all cases except those that could carry the death penalty. Skakel, who was charged in 2000, was not charged with a capital offense.

"The prosecution of state of Connecticut vs. Michael Skakel should never have been brought," said Skakel's attorney, Hope Seeley. "He should never have been incarcerated the last 2 1/2 years."

Prosecutors contend Connecticut has never set a deadline to try murder cases. They say that the nature of the crime, not the potential punishment, determines whether it is subject to the time limit.

"There's no other reasonable conclusion but that the Connecticut Legislature never intended to bar the prosecution of murder based on the passage of time," said prosecutor Susann Gill.

Skakel did not attend the hearing. The court was not expected to make a ruling on Friday.

Moxley's mother, Dorthy Moxley, said Skakel was trying to get out of prison through a legal loophole.

"If Michael is released because of the statute of limitations, it just means that once again someone can say 'Ha, ha, I got away with murder and I'm out of jail,'" she said outside court. "I know he's guilty and he will always be a felon and I will always know he did it."

Mrs. Moxley said she believed "there's some good to Michael." Her son, John, promptly disagreed.

"I think Michael Skakel is evil," he said. "I think the whole family is evil."

Several of Skakel's siblings attended the hearing, including his older brother, Thomas, who was an early suspect in the killing because he was the last person seen with Moxley.

"Does anyone think for any minute Martha would be happy knowing that someone is behind bars that didn't do it?" Thomas Skakel said.

Authorities say Skakel, a nephew of Ethel Kennedy, beat Moxley to death with a golf club. They also accused Skakel's wealthy family of a cover-up to thwart his prosecution.

Some of Skakel's friends and classmates testified that he was romantically interested in Moxley and was jealous because his older brother was competing for her affections.

Skakel's defense also argued that prosecutors failed to hand over a police sketch that they said resembled an earlier suspect.

"There's no doubt that jurors like visual evidence," Seeley said. "The sketch was favorable to the defendant. The suppression of the sketch was prejudicial."

Prosecutors said the defense received all the police reports that led to the sketch being made, and was given written notice that the sketch existed. They also said the sketch was of another resident in the neighborhood and that Skakel's investigator had interviewed the security guard who saw the man that led to the sketch.