A University of Pennsylvania professor was charged Monday with beating his wife to death in their suburban kitchen after she told friends she planned to divorce him.

Rafael Robb, a 56-year-old economics professor and expert in game theory, had told investigators he was in Philadelphia when his wife was killed Dec. 22.

Prosecutors, however, said his alibi didn't hold up.

Montgomery County District Attorney Bruce Castor has said the scene was staged to look like a burglary.

"Dr. Robb lied to the police about an obvious motive for this murder, his knowledge of his wife's recent plans to divorce him and obtain a significant portion of his wealth," according to an affidavit by Upper Merion police Detective David Gershanick.

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Robb had said he took the couple's 12-year-old daughter to school that morning and last saw his wife alive before driving to work. He said he returned home later that day and found her body.

Authorities said Ellen Robb's injuries were so extensive they initially thought she was killed with a shotgun blast to the face. The murder weapon has not been found.

Ellen Robb, 49, had told relatives and others that she had hired a divorce attorney and was expecting $4,000 a month in spousal support, prosecutors said in court papers.

Rafael Robb was charged with first- and third-degree murder, possession of an instrument of crime, tampering with evidence and lying to authorities.

His lawyer, Francis Genovese, did not immediately return a call seeking comment Monday.

Robb has been at Penn for at least four years, according to a resume posted on his university Web site. Penn officials said earlier that they had arranged for someone else to teach Robb's graduate seminar in game theory this semester.