Prosecutors announced Friday that no charges will be filed against a former California Highway Patrol officer accused of sexually assaulting a woman he and another officer followed home instead of investigating her for driving under the influence.

Supervising Deputy District Attorney Andrea Kohler said a review of the evidence and law determined that Jose Davila's conduct was unprofessional and inappropriate. Nevertheless, there existed reasonable doubt as to whether criminal conduct occurred.

"This equates to a lack of proof beyond a reasonable doubt, the standard by which all criminal cases are judged," Kohler said in a news release.

That doesn't mean something disturbing didn't happen that night, Kohler said. For one, the officers didn't conduct a thorough DUI investigation when called to the scene.

For another, the evidence shows a sex act was committed, Kohler said, and it occurred while Davila was on duty.

But she said there wasn't enough evidence for prosecutors to reasonably believe they could get a conviction against Davila.

"The case is, 'Was this a rape?'" Kohler said.

Kyle Humphrey, Davila's attorney, said it was not. Humphrey said he wasn't surprised by the DA's decision not to charge Davila, and he agrees with his client that no criminal act took place.

"My client acknowledges he used very poor judgment," Humphrey said. "But what he did wasn't a crime."

Humphrey said Davila is married and has been working hard to repair the damage his actions have caused his family.

Davila and the other officer, whose name has not been released, resigned from the CHP on Oct. 5. Humphrey said Davila resigned to spare his fellow officers further embarrassment as the investigation continued.

Cleve McKnight, attorney for the woman who made the allegations against Davila, could not be reached for comment.

Kern County sheriff's investigators recommended that Davila be charged with assault under the color of authority.

The investigation into Davila and another officer began in mid-September.

The woman told detectives she was stopped by a Kern County Sheriff's deputy while driving about 2 a.m. Sept. 14 in the area of Merle Haggard Drive and Highway 99, according to deputies. The deputy suspected her of driving under the influence and requested the California Highway Patrol respond to the scene.

Deputies said two CHP officers, one of them Davila, arrived at 2:38 a.m., and the sheriff's deputy who made the initial stop left. The woman told detectives that the officers offered to follow her home instead of arresting her.

The woman told deputies one of the officers -- later identified as Davila -- sexually assaulted her after following her home, according to deputies. The name of the other officer has not been released since no criminal charges were recommended against him.