Robb, 57, testified Monday that he argued with his wife about a trip she and their daughter were taking over the holiday break. He did not want the 12-year-old to miss any school.

"We started a discussion about that. The discussion was tense," Robb said. "We were both anxious about it. We both got angry. At one point, Ellen pushed me. ... I just lost it."

Robb said he picked up the chin-up bar, which was lying nearby, and struck his wife with it repeatedly.

He later threw the weapon in a trash bin in Philadelphia and tried to make their home look as if it had been burglarized. Detectives were suspicious from the start, though, because the scene was poorly staged and nothing was missing.

The 49-year-old homemaker was found dead in the kitchen, near the partially wrapped presents.

Robb's trial had been scheduled to start Monday. He could have faced a life sentence if convicted of first-degree murder, but prosecutors felt there were no guarantees given the circumstantial evidence.

The professor pleaded guilty to one count of voluntary manslaughter, which is defined as an intentional, unlawful killing, with provocation, in the heat of passion.

Montgomery County prosecutor Bruce Castor called the case "a classic heat-of-passion killing."

Robb adored his daughter Olivia and feared he would see less of her in a divorce, both sides agreed.

University spokesman Ron Ozio said a Penn official spoke to Robb's lawyer after Monday's hearing and asked for his resignation.

Ellen Robb's brothers, Art Gregory of Haddonfield, N.J., and Gary Gregory of Boston, said their sister suffered verbal abuse throughout the marriage, eroding her self-esteem.

"What kept them there was their undying love for their daughter Olivia," said Art Gregory, who is now raising the girl. "Both of them put Olivia first, beyond anything else, unfortunately to a very tragic end."

Rafael Robb apologized to Olivia, who was not in court, and said he was "very remorseful."

"I know she liked her mother. ... And now she doesn't have a mother," he said, stifling tears.

Robb, who has been held without bail, talked to his daughter by phone over the weekend and admitted that he was responsible for her mother's death. They have not seen each other since his arrest in January.

Sentencing will likely take place in a few months. Guidelines call for a prison term of 4 1/2 to seven years, but Castor said the statute allows for anything from probation to 10 to 20 years.

Rafael Robb, once a tenured economics professor at the University of Pennsylvania, faces a prison sentence of no more than seven years for bludgeoning his wife, Ellen, on Dec. 22.

Robb, 57, said Monday that he got into an argument with his wife about a trip she was taking with their daughter and whether they would be returning in time for the daughter to return to school.

"We started a discussion about that. The discussion was tense," Robb said. "We were both anxious about it. We both got angry. At one point, Ellen pushed me. ... I just lost it."

An indictment unsealed Thursday in U.S. District Court accuses Clinch County Sheriff Winston Peterson of perjury, obstruction of justice, using forced labor and extorting former jail inmates.

Peterson, 62, pleaded not guilty to the charges Thursday and was released on $10,000 bond.

Investigators say the sheriff charged jail inmates $18 per day for room and board. County officials agreed in April 2006 to return $27,000 to hundreds of inmates who paid the fees between 2000 and 2004. Peterson also used an inmate to do work at a business run by his wife, investigators say.

The sheriff is charged with obstructing justice by alerting an unindicted co-conspirator about the identity of an FBI informant he believed was part of a criminal investigation into courthouse activities. He is also accused of lying during a grand jury investigation of a Superior Court judge.

Neither Peterson nor his attorney could be reached for comment Thursday night. An after-hours call to his attorney's home went unanswered, and the sheriff could not be reached through the dispatcher.

Peterson is the latest Clinch County official to be caught up in investigations into the rural county's practices.

Superior Court Judge Brooks E. Blitch III and Chief State Court Judge Berrien Sutton face allegations by the Judicial Qualifications Commission, a state agency that investigates Georgia judges and has power to recommend removing them from office. They have not been charged with any crimes.

Blitch, 72, is accused of ordering illegal payments to county employees, ordering the early release of imprisoned felons and presiding over a case involving his son.

Blitch's attorneys have said an investigation will prove he is innocent.

Sutton is accused of appointing non-lawyers to hear criminal cases, pressing a magistrate judge to help one of his business associates and signing an illegal order to collect court fees that were later distributed to county officials.

Thomas Whithers, an attorney for Sutton, said Wednesday the judge looks forward to his day in court. "Judge Sutton has done nothing wrong and will vigorously defend these allegations," he said.

Deandre Witherspoon, 24, pleaded guilty Monday to second-degree murder in the killings of Orlando Herron, 13, and Darren Johnson, 11. The two were found shot in the head inside their ransacked home in February.

Authorities have said the boys were the victims of a drug-related robbery of their older cousin, an admitted drug dealer who survived being shot at the home.

Witherspoon, the sixth and final suspect in the case, avoided a potential life sentence by agreeing to the plea. His trial was set to begin Tuesday.

He now faces 22 to 40 years when he is sentenced Nov. 12.

Separate juries earlier this month returned guilty verdicts against Sonya O'Neal, 38, and Robert Reed, 36. They face mandatory sentences of life in prison when they are sentenced Wednesday.

Prosecutors said Witherspoon hatched the plan to rob the boys' cousin of drugs and money, and O'Neal did the shooting. Three others have pleaded guilty.

Two co-defendants, one of them a Mesa man, pleaded guilty to reduced charges Tuesday in the O.J. Simpson armed-robbery case, agreeing to testify against Simpson and three others in the alleged theft of sports collectibles from two memorabilia dealers.

Behind the scenes, prosecutors prepared to file an amended criminal complaint increasing the number of charges in the case to 12, including a second felony charge of coercion against Simpson and two new coercion charges each against the three remaining co-defendants.

The new complaint also alleges Simpson and Charles "C.J." Stewart conspired to persuade others to tell authorities that no guns were used.

The revised document, obtained by the Associated Press, removes Walter Alexander of Mesa and Charles Cashmore from the case, while naming Thomas Riccio in the Sept. 13 meeting between Simpson and memorabilia dealers Bruce Fromong and Alfred Beardsley.

Riccio, who was given immunity from prosecution, is expected to join Cashmore and Alexander in testifying for the prosecution.

Alexander pleaded guilty to the felony of conspiracy to commit robbery.

The district attorney said he would seek a suspended sentence for Alexander, a golfing buddy of Simpson's. "I'm very much at peace at what I've done today and what I'm going to continue to do," Alexander said as he clutched a Bible outside court. "I'm not here to try to hurt or help O.J. Simpson. I'm only here to tell the truth."

Late on Monday, the Nevada State Supreme Court agreed to a request by the American Civil Liberties Union of Nevada to stay the execution pending an upcoming ruling by the U.S. Supreme Court on the constitutionality of execution by lethal injection. The country's highest court agreed on September 25 to review the issue, the same day Castillo was scheduled to die.

The Nevada court also said the state's methods are cruel and unusual because the prisoner is so heavily sedated it is impossible for witnesses to determine the actual effects of the injection, effectively violating First Amendment rights.

The ruling is an effective reprieve because Castillo's execution order is only good for a week, and the U.S. Supreme Court is not expected to rule before then. A number of states, including California, have halted executions pending the legal review of whether the current method of lethal injection constitutes cruel and unusual punishment.

Castillo had given up his remaining appeals, saying he was ready to die for bludgeoning an 86-year-old Las Vegas teacher to death in 1995.

Castillo worked on Isabel Brendt's roof, then returned with a female companion after finding a house key. He burglarized the home and beat Brendt to death with a tire iron. They later burned down the home.