DUBLIN, Calif. -- A California doctor is accused of taking hundreds of photographs of different patients while they were unconscious and semi-nude at his medical clinic.

A $1 million arrest warrant has been issued for Dr. Tony Shiu, who also is accused of sexually battering two men at his home. Shiu is in private practice in Dublin, Calif. However, he disappeared after the warrant was issued. Authorities believe he has left the San Francisco Bay area.

A search of Shiu's home turned up about 450 digital photographs of 19 male patients who were unconscious and undressed in medical examination rooms. Only two of the patients photographed have been positively identified, police said. Those patients were not the two men who reported being battered at Shiu's home.

"You can imagine how shocked they were when we showed them naked pictures of themselves," Dublin police Sgt. Herb Walters said.

Police were alerted to Shiu after two men said they woke up at his home last August with no memory of the previous night. The men said they had drinks with Shiu. Shiu allegedly drugged the two men and raped one of them, Walters told the San Francisco Chronicle.

The men were taken to a hospital, where they tested positive for a drug that's commonly prescribed for anxiety but can cause memory impairment and confusion. Also, one of the men was found to have been sexually assaulted.

Police said one of the men had known Shiu for years, but the other had just met him the night of the alleged attack.

The Chronicle reported that the men said they met Shiu at his home with plans to meet friends in Oakland and Emeryville for an evening out in San Francisco. But after having two drinks each after arriving at Shiu's home, they lost all memories of the rest of the night, Walters told the paper.

"Witnesses told us that they made it to Oakland and Emeryville, but that the two men were too far out of it to continue to San Francisco," Walters said.

Walters said it is believed that Shiu drove them back to his home after that. When the men woke up the following morning, they became suspicious. That's when they went to a hospital for examination.