Professor provides a DNA sample

Investigators took DNA and fingerprint samples yesterday from University of Pennsylvania professor Rafael Robb, whom District Attorney Bruce L. Castor Jr. now regards as the leading suspect in the bludgeoning death of Robb's estranged wife.

While Castor described the move as routine, he also released a search warrant affidavit laying out a web of suspicion about the circumstances of Ellen Robb's Dec. 22 murder - and her husband's account of his actions that morning.

"The evidence so far indicates circumstantially that Dr. Robb may have had a part in this killing," the Montgomery County prosecutor said at an afternoon news conference.

That evidence, Castor added, is not yet enough to make an arrest.

"I am not going to go forward and make an arrest until I am confident he is the right suspect," the district attorney said.

Robb's defense attorney, Frank Genovese, of Norristown, did not return a call yesterday seeking comment. In previous interviews, Genovese has proclaimed the economics professor's innocence.

Robb is an expert in "game theory," generally described as a method of studying situations in which players choose various tactics in an effort to maximize outcomes. He teaches at Penn's School of Arts and Sciences.

Castor said he did not expect the case to hinge on DNA evidence, since Rafael Robb lived at the home. However, if an unknown DNA sample is recovered from the crime scene, it could point to a different or additional suspect. Test results could be available by next week.

Ellen Robb, 49, was bludgeoned beyond recognition in the kitchen of her home in Wayne. The wounds were so severe that veteran detectives thought she had been shot until an autopsy proved otherwise.

The Robbs, long estranged but still in the same house, were on the verge of separating, according to friends and relatives quoted in the affidavit. Ellen Robb had retained a divorce lawyer, they said, and was planning to move into a $1,500-per-month apartment by New Year's Day. According to a real estate agent who had met with her, Ellen Robb said she expected to receive $4,000 in monthly support from her husband.

The search warrant affidavit, quoting two mental-health experts, calls the killing a "blitz attack" by someone with "a need to depersonalize Ms. Robb such that she is hardly recognizable as a human being."

That did not square, Castor said, with Rafael Robb's explanation that his wife had likely been killed by a burglar who broke through the glass of a rear door.

Burglars rarely enter occupied homes, Castor said, and generally flee if confronted.

Nothing appeared to be stolen from the house, the affidavit said. The broken back-door window "appears staged," the affidavit says, since the shattered glass on the floor had not been trod upon.

It is likely that the sound of the window shattering would have alarmed Ellen Robb, who instead appeared to have been wrapping Christmas presents when attacked. The affidavit also questions whether a burglar would have taken time to restrain the family's dog, which was found closed in a bedroom.

Investigation of Rafael Robb's statements to detectives also aroused suspicion, the affidavit said. He claimed to have spent up to 40 minutes buying fruit at a market in Philadelphia on his way to work that morning. A cashier did identify him as a regular customer, but said he had not been there the day of the murder.

Robb said that when he came home to find his wife's body, he did not immediately call 911, the affidavit said. Instead, he said he "touched her face," put his laptop computer and briefcase in his upstairs bedroom, checked on the dog barking in his daughter's bedroom, and, after returning downstairs in search of a phone, found the broken door window.

The affidavit says there were working phones in both upstairs bedrooms. It also says that the apparent killer tracked blood out of the house with heavy-treaded boots. Rafael Robb told investigators he had several pairs of work boots, but none was found in the house.

"He told the police dispatcher that he believed she was dead because her head was cracked," Castor said. "That is very significant to me," given the initial impression of investigators that she had been shot.

"He has both motive and opportunity," Castor said, "and right now he has a lot of explaining to do."