Kennedy cousin Michael Skakel launched a barrage of criticism Thursday against the attorney who represented him at his murder trial, portraying an overly confident lawyer having fun and basking in the limelight while making fundamental mistakes from poor jury picks to failing to track down key witnesses.

Skakel testified in his latest appeal, arguing that trial attorney Michael Sherman failed to competently defend him when he was convicted in 2002 of killing his Greenwich neighbor in 1975 when they were both 15. Skakel, the 52-year-old nephew of Robert F. Kennedy’s widow, Ethel Kennedy, is serving 20 years to life for the golf club bludgeoning of Martha Moxley.