LOS ANGELES: A US man convicted eight years ago of murdering his wife and unborn son in a high-profile case has appealed to California's Supreme Court, officials said Friday.

Scott Peterson was found guilty in 2004 of suffocating his pregnant wife Laci and dumping her body in San Francisco Bay on Christmas Eve 2002, but has always maintained his innocence.

His lawyer Cliff Gardner filed a 427-page appeal to California's highest court on Thursday, said court clerk Cecilia Wong.

"The appellant's opening brief was filed yesterday," she told AFP, adding that the respondent's brief is now due on May 21, 2015, although there may be other developments in the case before then.

Peterson claims his wife was killed sometime after he left their home in Modesto, California on December 24, 2002, to go fishing in San Francisco Bay, according to the Los Angeles Times.

His attorneys says media coverage surrounding the case influenced the jury, even though the trial was moved from Stanislaus County to San Mateo County in order to reduce the impact of publicity.

"Before hearing even a single witness, nearly half of all prospective jurors admitted they had already decided Mr Peterson was guilty of capital murder," Gardner said, cited by the newspaper.