Economics professor Rafael Robb pleaded guilty to voluntary manslaughter in Montgomery County court this morning.

Robb, 57, admitted to having killed his wife, Ellen, in the couple's Upper Merion home on Dec. 22, 2006. Rafael Robb said in court that he killed Ellen Robb with a chin-up bar after the couple had an argument about whether their daughter, Olivia, would return from an upcoming vacation before the end of Christmas break.

"I just lost it," said Robb, who also apologized to Ellen's family - more than a dozen family members and friends were in the courtroom - his own family and his daughter.

Robb's trial, in which he would have faced first-degree murder charges, was scheduled to begin Monday. If convicted, he would have faced life in prison.

Montgomery County District Attorney Bruce Castor filed the manslaughter charge Monday morning, after it became clear Robb would admit to the crime.

With the plea, Robb will receive a considerably lighter sentence. Standard sentencing guidelines call for 4 « to 6 years in prison, though Castor said he would seek a "substantial" sentence above the guidelines. The maximum sentence Robb could receive is 10 to 20 years in prison.

Sentencing will likely take place in about four months, defense attorney Frank DeSimone said.