Robert A. Durst, the New York multimillionaire who admitted that he had butchered his 71-year-old neighbor's body with a bow saw and dumped the parts into Galveston Bay, was acquitted of the man's murder on Tuesday. Mr. Durst told the jury that despite what happened afterward, the killing itself had been accidental and an act of self-defense.

For many in the courtroom, it was a surprise ending to a strange trial. When a bailiff read the verdict, in a scene televised live nationally, Mr. Durst, who had faced up to 99 years in prison, looked stunned, his mouth agape as he gazed upward. A tight smile spread across his face. Moments later, he hugged his defense lawyers, softly saying, ''Thank you, so much.''

In a certain sense, the verdict was no more unlikely than anything else heard over six weeks of testimony: a troubled multimillionaire, described by his lawyers as suffering from mild autism, living on the cheap disguised as a woman; the unsolved disappearance of his first wife; the unsolved murder of his confidante in Los Angeles; a secret second marriage; a fatal shooting and a grisly cover-up; a nationwide manhunt that ended with a shoplifting arrest.

Members of the jury, which deliberated over four days, said at a news conference after the verdict was read that there were holes in Mr. Durst's story, but that ultimately the prosecution had failed to prove that he deliberately murdered his neighbor, Morris Black. ''The defense told us a story and stuck to it,'' said Chris Lovell, a juror. ''The D.A. gave us multiple scenarios of what may have happened.''