Daniel Horowitz, who regularly appears on television as a legal analyst, telephoned police on Saturday night and said that the body of his wife, Pamela Vitale, was lying in the entry way to their home in San Francisco.
Police have not yet indicated how she was killed but said they were treating it as murder. "We're talking to several individuals," said Jimmy Lee, a spokesman for the sheriff's department.
"Nobody's in custody right now. We are following up on some leads as well as trying to establish a motive and suspect information."
Mr Horowitz is a regular contributor to television channels such CNN, MSNBC and Fox News. He regularly appeared as a commentator during the Laci Peterson murder trial, in which Scott Peterson was eventually convicted of murdering his wife and his unborn child. Earlier this year, Peterson was sentenced to death.
His current case involves defending Susan Polk, who is accused of murdering her husband in the poolhouse of their California home in 2002. Just last week, a jury listened to opening statements in the case, which centres on a bitter divorce battle. Jurors visited the house where Mrs Polk, 47, is said to have murdered her 70-year-old husband. Mr Polk had been the woman's therapist when she was a troubled teenager and they married when she was 24.
Mr Horowitz told reporters from the San Francisco Chronicle on Saturday that he was too shocked to comment on his wife's death. "I can't talk. I can't. It's beyond words," he said.
His co-counsel in the Polk case, Ivan Golde, also declined to comment on the circumstances of the killing or to speculate on how the murder might affect the trial with which they were both involved.
"Our hearts and prayers are with Dan and his family," he said.
Mr Horowitz's wife, a former executive in a hi-tech marketing company, worked at his law firm where she established and managed the company's computer databases.
Mr Horowitz met Mrs Polk while visiting her at the Contra Costa Jail while preparing for a television appearance. He became her attorney on the eve of trial.
He has defended numerous other people on trial for murder. During the Peterson trial last year, he repeatedly turned up at the San Mateo County courthouse with stacks of autobiographical material, offering his services to the media as a legal analyst. "You have to realise that publicity brings business," he told reporters at the time. "And [journalism] is fascinating."Reuse content