Prescott Sigmund pleaded guilty yesterday in the pipe bomb explosion in Northwest Washington that critically injured his half brother last year, reaching an agreement with prosecutors that calls for him to serve 32 years in prison.

The plea agreement marked a new chapter in a wrenching family drama. The victim in the July 12 bombing, 21-year-old Wright Sigmund, sat in the front row of the federal courtroom, at times teary-eyed, and said after the hearing that he was disappointed his half brother had appeared so "cold" and "without emotion."

Never glancing at Wright Sigmund or any of the other family members in the courtroom, Prescott Sigmund, 35, said little more than "yes, sir" and "because I'm guilty" in response to U.S. District Judge Emmet G. Sullivan's questions. In the 17-page plea agreement, he admitted planting two pipe bombs in his father's Chevrolet Blazer, which was parked in an underground garage at 5225 Wisconsin Ave. NW.

The bomb was intended for his father, Donald, a successful insurance executive, but instead injured Wright Sigmund when he went to the Blazer to run an errand for his father. Authorities have said that Prescott Sigmund was cash-strapped and hoped to benefit financially from his father's death.

In a six-page letter to Sullivan, the defendant's mother, Gwendolyn Sigmund, asked the judge to show "compassion" and placed blame for the car bombing on Donald Sigmund.

"When Scott sought help from his father, he received only ridicule, bullying and abuse," she wrote. "His dignity stripped away, Scott simply 'snapped' under the burden of years of cruelty inflicted by his alcoholic, rage-driven father."

Donald Sigmund, 65, did not attend the court hearing and did not return a message left on his cell phone.

Wright Sigmund's mother, Claire Phillips, also wrote to the judge, saying that her son "will innocently suffer a life time of pain and disability."

Phillips sat next to her son during the hearing and said afterward that "seeing Scott was like looking at this rapist who had raped my child."

Sullivan said he would withhold final approval of the plea agreement until he received a pre-sentencing report. Prescott Sigmund's attorney, David Bos, declined comment on the agreement.

During yesterday's proceedings, Assistant U.S. Attorney Jeanne Hauch laid out the government's case, saying Sigmund spent several weeks planning the bombing, using his computer to help create a fake driver's license and birth certificate.

Under the fictitious name Paul Baillie, he purchased two cans of gunpowder at a Silver Spring gun shop, Hauch said.

Three days after the bombing, Sigmund vanished from his Potomac home, leaving his wife and their two young children. Shortly afterward, his wife learned that he had emptied their bank accounts. She also discovered that her husband had been fired from his job nine months earlier.

On Nov. 9, the TV show "America's Most Wanted" ran a feature on Sigmund, which prompted him to turn himself in to authorities in Missoula, Mont. He had started a new life in Missoula, assuming a different name, working as a motel desk clerk and telling people that his wife and children had been killed by a drunk driver.

Sigmund's wife, Bradey Bulk Sigmund, who attended yesterday's hearing, expressed satisfaction with the plea agreement. "I was hoping he would plead so we wouldn't have to go through a trial," she said.

Outside the courthouse after the hearing, Wright Sigmund said he has undergone numerous surgeries because of his injuries, is intensely involved in physical and psychological therapy and takes 57 pills a day. He said he tried to return to college this winter but dropped out. He plans to return this fall.

He said that he was disappointed Prescott Sigmund never looked at him during the hearing and that he could not believe the "conniving criminal mind he had."

But he said the plea agreement "made me feel a lot better . . . like justice has been done."

Asked if it would have made a difference if his half brother had called him at some point to say that he didn't mean to harm him, Wright Sigmund broke into tears.

"It would have made all the difference in the world," he said.

Bombing victim Wright Sigmund tries

to recover his composure outside the courthouse after making a statement.Bradey Sigmund, wife of pipe bomb suspect Prescott Sigmund, comforts Wright Sigmund outside the federal courthouse during the trial.