On Wednesday in Hartford, those judges heard testimony to determine if Skakel – who was convicted in 2002 of murdering his neighbor before the conviction was reversed – will receive a new trial or whether he will be sent back to prison to finish his 20-year to life sentence.
Skakel's attorney, Hubert J. Santos, contended that the justices should uphold a lower court's ruling that overturned Skakel's conviction on the grounds that his original defense attorney, Mickey Sherman, was inadequate.
Santos told the panel the inadequate defense included overlooking an alibi witness and not focusing on Michael's brother, Thomas, as a possible suspect. Santos alleged that Sherman was consumed with financial troubles and a celebrity lifestyle.
"When you cut through all that happened, this defendant did not get a fair shake," Santos told the judges.
Prosecutors argued that an overwhelming amount of evidence shows Skakel murdered Martha Moxley in 1975 and that Sherman's defense was thorough.
"This was far from a slipshod defense," Susann Gill, a supervisory assistant state's attorney, told the court. "This was a well thought out defense."
Gill added: "You would be hard pressed to find a case with so much evidence."
Skakel, 55, is a nephew of Ethel Kennedy. He was convicted in 2002 of bludgeoning neighbor Moxley to death with a golf club in 1975 when both were 15-year-olds in Greenwich, Ct.
Judge Thomas A. Bishop had set aside the murder conviction of Skakel, ruling that Sherman had not represented him effectively. Prosecutors have appealed that decision. Since November of 2013, Skakel has been free on $1.2 million bail.
The court could take several months to render a decision, Skakel attorney Stephen Seeger has told PEOPLE.
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Robert F. Kennedy, Jr.: Skakel 'Didn't Get a Fair Trial and Is Not Guilty'After the hearing's conclusion, Martha's mother, Dorthy, who sat just feet away from Skakel in the courtroom, told PEOPLE she remains convinced that Michael killed her daughter.
"I want him back in jail to serve his sentence," she said, "and then he can go."
"I can't wait until it's all over," she said. Of sitting in the same room with Skakel, she said, "It doesn't make me happy."
Skakel's cousin and staunch supporter Robert F. Kennedy, Jr., who sat next to Michael in the packed courtroom, was optimistic that the judges would "absolutely" uphold Judge Bishop's 2013 decision.
"He had a terrible lawyer," Kennedy said today. "He didn't get a fair trial and he is not guilty."
Kennedy says that Skakel was 11 miles away from the scene of the crime with five witnesses at the time "everyone agrees this murder took place, at 10 o'clock at night. An ironclad alibi, and the only reason he was convicted is that he had the worst lawyer in the state of Connecticut."
Kennedy has been doing his own investigation into who killed Martha and is coming out with a book on his findings in April.
He says it was not Michael or his brother, Thomas, who killed Martha, and that "there is overwhelming evidence that two other people committed this crime." He says that one alleged killer lives in Bridgeport, Ct. and the other in Oregon.
However, Kennedy says authorities never investigated the two and "they never did the real footwork."
"[The two] admitted to being there that night, they admitted they planned to kill Martha Moxley," said Kennedy. "That kind of stuff, if it was part of the trial, Michael would never have been convicted."
Many Skakel friends and relatives showed up to support him, including a brother, Stephen Skakel, and cousin Douglas Kennedy, Robert Kennedy, Jr.'s younger brother.
"He is a wonderful, wonderful human being," a female Kennedy cousin told PEOPLE of Michael. "Generous, thoughtful, he would not hurt a flea. I know he is innocent."
Michael and his attorneys did not comment.