The case was tabloid fodder and its legal twists and turns transfixed much of the country. In 1975, a 15-year-old girl was found slain in an affluent Connecticut suburb, bludgeoned to death with a golf club. Michael C. Skakel, a neighbor and a cousin of the Kennedys, was ultimately charged and found guilty of murder, but his conviction was overturned by the state’s highest court.
On Friday, prosecutors announced that Mr. Skakel, 60, would not face a second trial, effectively ending a long fought, notorious case that reached all the way to the Supreme Court.
Proving the guilt of Mr. Skakel, who was convicted of killing Ms. Moxley in 2002, would be impossible because many of the key witnesses in the case had died, prosecutors said.
The announcement came exactly 45 years to the day Ms. Moxley was killed in Greenwich. She had been hit so hard with a golf club that it broke. A piece of the shaft had been used to stab her in the neck.
It took 25 years for investigators to charge Mr. Skakel as the case stalled because of a lack of physical evidence. Mr. Skakel was found guilty after a three-week trial but lawyers who appealed his conviction maintained that their client had received poor representation.
Two years ago Connecticut’s highest court, agreeing with Mr. Skakel’s argument, vacated his conviction, citing shortcomings in his defense. Last year, the United States Supreme Court rejected prosecutors’ attempts to revive the case.
“We’ll never forget Martha, and I would think Michael is very regretful,” said Ms. Moxley’s mother, Dorthy Moxley.
Kristin Hussey contributed reporting.