Less than three months after taking control of Denver’s police, sheriff and fire departments, Manager of Safety Ron Perea resigned Monday amid growing uproar over how he disciplined officers.

Perea brushed aside concerns earlier this month from other city officials who feared he was too lenient in refusing to fire three officers involved in two separate police abuse cases — including a highly publicized case in which video shows police beating a man in Lower Downtown.

But his decisions in those cases started to unravel in the past seven days.

After a meeting Monday afternoon between Perea and Mayor John Hickenlooper, Perea returned to his office at the downtown police headquarters and told confidants that he had resigned.

“I appreciate the opportunity to serve as manager of safety for the city and county of Denver,” he said in a handwritten note on the mayor’s stationery. “I respectfully tender my resignation effective August 31, 2010.”

Later in the afternoon, the mayor’s office sent out a news release announcing the resignation. The mayor, in a later news conference, said Perea resigned voluntarily.

Hickenlooper said Perea told him he didn’t feel he could build trust with the public given the controversy his decisions had created.

“Once he put it it in that context, it was hard to argue with,” Hickenlooper said. “It would be very difficult to rebuild after all the events of the last four or five days. It would be very hard to rebuild that trust.”

The police department last week announced it would reopen an internal investigation into a case in which officers accused of covering up the LoDo beating were docked three days’ pay by Perea. Hickenlooper requested the FBI review the officers’ actions after the video was widely circulated on news stations and the Internet.

City Councilwoman Judy Montero, who last week demanded that Perea reverse one of his discipline decisions or resign, said she thought Perea did the right thing by resigning.

“We as a community, a diverse community, had worked so hard for so many years building that trust with law enforcement, and it was diminishing so quickly,” Montero said. “Now it’s time to start rebuilding.”

The mayor said that Police Chief Gerry Whitman had assured him that incidents of police brutality were isolated.

“Our police department is not out of control, and day in and day out our officers are doing everything they can to keep our city safe, and they certainly are respecting the rights and liberties of all of our citizens,” the mayor said.

Perea did not respond to requests for comment.

Earlier Monday, Perea moved to rescind his earlier discipline order suspending police Officer Eric Sellers 45 days without pay for beating a young man who had complained when Sellers declined to press charges against a man who hit the 23-year-old. Perea had suspended Sellers for “inappropriate force” and “commission of a deceptive act.”

Both the city attorney’s office and Independent Monitor Richard Rosen thal, who reviews investigations into alleged police misconduct, had warned Perea he needed to undo what they viewed as light discipline for Sellers because they feared it would undermine a new discipline system the city took six years to put in place.

In that case, Perea found Sellers lied about his actions, cause for “presumptive termination” under the new guidelines. But Perea found mitigating circumstances, because the case languished under previous safety manager Al LaCabe.

Rosenthal and the city attorney’s office feared that if Perea’s decision stood, the police union would be able to appeal discipline decisions based on the length of time it took to complete investigations into alleged wrongdoing.

The mayor brushed aside concerns from union officials that it had taken LaCabe too long to decide how to handle the controversial abuse cases.

He said LaCabe had worked 60 to 70 hours a week and had put his “heart and soul” into making the city safer.

LaCabe declined to comment for this story.

David Bruno, a lawyer for the Denver Police Protective Association, decried the moves to rescind the discipline of Sellers and to reopen the investigation of Officer Devin Sparks and Cpl. Randy Murr in the LoDo beating case.

Bruno said that in more than 30 years of representing police officers, he had never seen discipline decisions reversed by a safety manager.

He said the public should question whether “the outcry of special interests or the media” was controlling the outcome of those cases.

“My fear is that either a citizen or an officer will now be hurt if an officer hesitates in the slightest degree to do what he believes is appropriate in the circumstance without the cloud of fear that behind him is the monitor dictating what the monitor, as an armchair quarterback, believes 20 months later is appropriate conduct,” Bruno said.

Perea will spend his final days on the job working on finalizing budgets for the city’s police, fire and sheriff departments, Hickenlooper said. He has no discipline cases pending.

The mayor said he is appointing Deputy Safety Manager Mary Malatesta as interim safety manger until a replacement can be found. She will handle the final discipline decisions for Devin, Murr and Sellers.

Christopher N. Osher: 303-954-1747 or cosher@denverpost.com