BUFFALO, N.Y. — Daniel Derenda is no longer Buffalo's police commissioner. His abrupt retirement went into effect at midnight.

City officials say Derenda is leaving to pursue an opportunity in the private sector.

Derenda was with the Buffalo Police Department for more than 30 years. He became commissioner in 2010.

According to Mayor Byron Brown, Derenda's decision was his alone, and he was not pushed to leave his post.

"No, I had no plans to ask him to step aside," said Brown, D-Buffalo. "He has served the city well. He's done a good job. Crime has fallen by 40 percent overall during my tenure as mayor. Commissioner Derenda has been the commissioner for seven years."

Brown said he knew Derenda was considering a job opportunity in the private sector for about a week before the decision. 

Amid recent cuts in overtime for police, Brown says Derenda's departure is not related to budget problems. He admits the extensive search for fallen officer Craig Lehner in the Niagara River last fall did affect the department's finances.

"Certainly that had an impact," Brown said. "We were focused on bringing one of our own home, finding officer Lehner and certainly there was a cost involved to doing that."

Brown has tabbed Byron Lockwood from deputy to acting commissioner while looking for Derenda's permanent replacement. That person will head a department that has faced criticism for several issues, including its Strike Force Unit and police checkpoints. The city is also preparing for a new combined police and fire headquarters in the future.

"We are constantly, always looking for new ideas," Brown said. "There are a number of very talent people in the Buffalo Police Department and I'm confident we'll be able to find the right person within the Buffalo Police."

Brown has 180 days to name a new police commissioner.