A lawyer for Kennedy cousin Michael Skakel told a panel of Connecticut judges Tuesday that his client's 20-years-to-life prison sentence for killing his teen neighbor in 1975 was excessive.

Skakel, who was convicted in 2002 of beating 15-year-old Martha Moxley to death with a golf club in wealthy Greenwich, also addressed the court, saying, "I didn't commit this crime."

Skakel's lawyer told a three-judge panel that Skakel was 15 at the time and would have been tried in juvenile court where the maximum sentence would have been four years.

Skakel, who appeared handcuffed and in an orange jumpsuit, maintained his innocence and said he was "baffled" by the legal process and pleaded with the judges to allow "the truth" to come out, CTnow.com reported. 

"I've taken a pol-- I've taken -- give me a polygraph. I've passed three sodium pentathol tests. I don't know what else to say," Skakel told the panel. "As I've said it before, I pray for Mrs. Moxley every day."

The judges did not immediately rule on a decision. 

Prosecutors said the sentence was appropriate and pointed out he could have been tried in adult court in 1975.

Moxley's brother, John, also addressed the panel of judges, saying, "Michael belongs in jail for the rest of his life."

Moxley's mother, Dorothy, echoed her son's sentiments, telling CTnow.com that Skakel should not be released from prison.   

"I'm so convinced Michael did this .... He made us suffer for 27 years," she told the station. "Look at all the years he was free and running around while we were such a mess trying to find out what happened, so why should he get out now?" 

Skakel's brother, meanwhile, told the station that his family "remains steadfast in his innocence."  

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The Associated Press contributed to this report.