LOS ANGELES, SEPT. 9 -- Prosecutors ended weeks of speculation and announced today that they will not seek the death penalty in the double murder case against former football star O.J. Simpson.

The decision, which had been delayed for weeks as a panel of assistant prosecutors wrangled with the issues involved, was announced with little explanation late today by the District Attorney's office, which in the past month had presented part of its case to a mock jury in Arizona and had questioned jurors in that exercise about a possible death sentence.

Prosecutors said they will seek a sentence of life without parole if a jury convicts Simpson, who is facing two first-degree murder charges for the death of his ex-wife and her friend. Multiple murder is a special circumstance under California law that allowed prosecutors the option of seeking the death penalty.

In a letter to Simpson's attorneys, Assistant District Attorney Frank Sundstedt, chairman of the six-member death penalty panel, said the decision was made after "consideration of all available aggravating and mitigating ... evidence."

The committee's guidelines would forestall the death penalty unless panel members believe that the evidence bearing on the issue is of "such convincing force" that a judge or jury would have no choice but to conclude that the aggravating circumstances, those that work against the accused, outweigh the mitigating circumstances, those that work in his or her favor.

Although District Attorney Gil Garcetti met with community leaders in July about the case, the letter from Sundstedt suggested that community feelings did not play a role in the decision.

"While the office is aware that there is deep public concern about whether the death penalty will be sought in a case, the decision must be made independent of this concern," the letter said.

"District Attorney Gil Garcetti reviewed and affirmed Mr. Sundstedt's decision in this case," the letter said.

Simpson's lead defense attorney, Robert L. Shapiro, said his office did not appear before the panel that considered the penalty decision.

"Our position was that since Mr. Simpson has unequivocally proclaimed his innocence, this was not an issue on which we could do any more than provide background information regarding the outstanding career and charitable works of O.J. Simpson," Shapiro told the Associated Press.

Suzanne Childs, a prosecution spokeswoman, said today that the families of Nicole Brown Simpson and Ronald L. Goldman, whose bodies were found fatally slashed on June 13, had been notified of the decision. Superior Court Judge Lance A. Ito, who had encouraged the prosecutor's office to quickly resolve the penalty question, also was notified although he is on vacation, she said.

The decision was heralded by African American leaders here, many of whom oppose the death penalty on moral grounds, and was criticized by legal experts who questioned why the prosecutor had delayed what they called a simple matter.

"I know it was not an easy decision for the district attorney," said John Mack, head of the Urban League of Los Angeles. Mack had met privately with Garcetti.

"Beyond the moral argument, there was the idea that although O.J. Simpson clearly had been guilty of terrible spousal abuse -- which is wrong -- he doesn't have a track record as a hardened criminal," Mack said. In 1989 Simpson pleaded guilty to battering his wife.

Harland Braun, a former prosecutor and a defense attorney, said the prosecutor's office created a bigger public controversy by waiting so long to make its decision on what penalty to seek.

"It was so obvious you wonder why they took so long. I couldn't imagine trying to send O.J. Simpson to the gas chamber. He had a relatively blameless life, he did a lot with his life," Braun said. Even if Simpson were convicted, Braun said, "He acted with emotion and killed someone he loved."

No matter what Garcetti decided, there will be critics, Braun said. "If he asked for the death penalty, he would have been accused of racism. If he didn't, he'll be accused of treating him like a celebrity."