Independent investigation launched into police department's handling of officer found drunk behind wheel

An independent investigation has been launched into the uniformed officer who was found passed out drunk in Aurora, Colorado.

Nathan Meier was found unresponsive behind the wheel of an unmarked police car and taken to a hospital in March, according to the Aurora Police Department, which said in a statement that some responding officers smelled “a very faint odor” that may have been alcohol.

The department faced outrage when the public learned there was no DUI investigation and no DUI charge against Meier. Aurora Police argued that the incident was treated as an emergency situation and there was no evidence of drinking at the scene.

“Due to an inability to exclude a medical condition and absent confirmatory information, a DUI investigation was not conducted,” a statement from Aurora Police said. “No blood test was done since there was no felony committed and a blood draw could not be forced.”

The Aurora Police Department announced in a statement last week that it had launched an internal investigation into the matter and that Meier “took immediate responsibility for his actions.”

Meier was demoted from the rank of agent to officer and “received a significant unpaid suspension,” the police department said, although he still remains employed.

In an internal email to the Aurora Police Department obtained by ABC News, Police Chief Nick Metz wrote on Friday: “I unequivocally stand by my decision regarding the involved officer.”

“I know cops are human beings. You are not perfect. You are exposed to higher levels of stress and trauma than the general public will ever truly understand,” Metz wrote. “We all know that trauma, suicide and substance abuse continue to be huge problems in our profession.”

Aurora City Manager Jim Twombly called on former U.S. Attorney John Walsh to review the Aurora Police Department’s handling of the case. He said the results of the investigation will be released to the public.

“It is in the public’s best interest that a thorough outside examination take place to ensure our residents’ confidence in our police department and its leadership,” Twombly said.

Law firm WilmerHale, where Walsh is a partner, confirmed that he will lead the independent review.

A spokesperson for Colorado's 18th Judicial District Attorney told ABC News the office is reviewing Meier's case to see whether there is enough evidence to charge him with DUI.

ABC News' Clayton Sandell contributed to this story.