The Police Department's internal affairs division is investigating an allegation that the lead investigator in the Robert Blake murder case withheld evidence from the defense and that police wrongly assumed the actor was guilty because of his celebrity status.

The complaint was filed nearly a year ago by M. Gerald Schwartzbach, who won Blake's acquittal in his criminal trial, and Brian Allan Fiebelkorn, a car dealership manager who testified at Blake's civil trial and was interviewed as a potential witness in the murder trial.

Fiebelkorn disclosed the matter to The Associated Press this week, concerned about the delay.

"All that I can say is a complaint was filed and it is under investigation," said Andre Birotte Jr., inspector general of the LAPD.

Blake, former star of the "Baretta" TV detective show, was acquitted in 2005 in the death of his wife, Bonny Lee Bakley, but a civil jury found that he intentionally caused her death and award her children $30 million.

Bakley was shot to death in 2001 outside a restaurant where she and Blake had dined.

The claim against the lead investigator, police Detective Ron Ito, alleges he did not adequately investigate the link between two former stuntmen who said Blake had asked them to commit the crime and Christian Brando, who had an affair with Bakley and was once thought to be the father of a child she had with Blake.

The claim also alleges that Ito withheld information from the defense that one of the stuntmen had used methamphetamines and another had been admitted to a mental ward.

LAPD spokesman Lt. Paul Vernon declined to comment, saying personnel complaint investigations were confidential.

Christian Brando, son of the late actor Marlon Brando, has denied any involvement in the killing, and defense attempts to link him to the shooting were barred from Blake's murder trial.