CINCINNATI — Mayor John Cranley on Thursday night emotionally apologized to the police union in Cincinnati after a proclamation was "mistakenly" issued in honor of a man who killed Officer Sonny Kim nearly two years ago.

The father of Trepierre Hummons posted a proclamation on Facebook deeming June 1 as "Tre Day," prompting Cranley to issue an apology letter to the Fraternal Order of Police and then break down in tears later during a news conference at the union hall.

"This was a huge mistake," Cranley said. "It's not done intentionally. It's human error, but the buck stops with me.

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"I love our police department," he said, breaking down in tears. "I would never do anything to hurt them."

Cranley paused.

"I'm sorry," he said.

Cranley said he has called Kim's family to apologize.

Kim was gunned down in Madisonville in June 2015.

The mayor's office receives several proclamation requests from citizens each week. The requests are handled by Cranley's deputy chief of staff, Holly Stutz Smith. The mayor's signature stamp is on the proclamations, but Cranley said he did not see the "Tre Day" proclamation before it was released.

Smith took responsibility for the mistake, but Cranley said it's ultimately his fault.

"Please know that I had no idea that this request had been made and would never give permission to issue a proclamation honoring the murderer of Officer Sonny Kim, a true public servant who sacrificed his life while protecting the safety of the citizens of Cincinnati," Cranley wrote in the letter to FOP President Dan Hils.

Cranley is a strong advocate for the police department and public safety has been among his top priorities since being elected in 2013. He was endorsed by the FOP in 2013 and was again ahead of this month's primary.

Cranley finished second behind City Councilwoman Yvette Simpson in the primary, and they'll face each other in the November general election.