San Antonio's police chief has decried the allegations against an officer accused of raping a handcuffed 19-year-old woman, saying it's "unthinkable."

Chief William McManus told reporters over the weekend he was "angry" and "outraged" after Officer Jackie Len Neal, an 11-year department veteran, was arrested Saturday on a sexual assault warrant.

According to an arrest affidavit, Neal asked the woman to step out of her vehicle about 2 a.m. Friday after tailing her for several blocks.

The affidavit says Neal told the woman her vehicle had been reported stolen. The document says the woman produced a sales slip, but Neal patted her down, ignoring a request for a woman to do that.

The affidavit says Neal placed the woman in handcuffs and raped her in the back of his car.