Authorities investigating the recent bludgeoning death of an Ivy League professor's wife believe the slaying was staged in order to look like a burglary, the district attorney said.

Investigators searched Rafael Robb's office at the University of Pennsylvania, but the economics professor denies having anything to do with Ellen Robb's death.

"It's not unusual in these investigations that they first start off closest to home," said Robb's attorney, Francis Genovese. "He is hopeful, as am I, that (authorities) are continuing to pursue all leads and not just focusing solely on him."

Ellen Robb, 49, was found beaten to death Dec. 22 in the kitchen of their house in upscale Upper Merion Township, just outside Philadelphia. Montgomery County District Attorney Bruce Castor on Thursday described it as "an exceedingly bloody crime scene" and said the attack was not random.

"Mrs. Robb was the specific target of this assault," Castor said.

Castor refused to call Robb a suspect, but said he had not been excluded either.

Though estranged, the couple lived together in the home with their 12-year-old daughter. Authorities are looking into reports that Ellen Robb had initiated divorce proceedings.

Rafael Robb told investigators that he last saw his wife alive before driving to work last Friday morning. The professor called police that day around 1:45 p.m. to say he found her body when he returned home.

A window in a door had been smashed, but Castor said several pieces of evidence led authorities to believe the scene was staged to look like a burglary. For example, broken glass from the door window had not been crushed underfoot or tracked throughout the house, Castor said.

"That strikes me as very unusual," he said.

Castor also noted Rafael Robb has not reported anything missing from the house.

Investigators have taken forensic evidence from the Robbs' home — including computers and financial records — and searched the couple's cars and the professor's office at Penn, Castor said.

Castor said investigators were interested in talking with members of the public who could discuss the professor's "personality, his habits, the way he interacts with people."

Rafael Robb, who is originally from Israel, earned a Ph.D. in economics from the University of California, Los Angeles, in 1981. He has been at Penn for at least four years, according to a resume posted on his university Web site. That site spells his last name "Rob," though his name is spelled "Robb" on other Penn sites.

A Penn spokesman referred calls to police.