Minneapolis Police Chief Brian O'Hara has resigned following an internal investigation into his conduct, the mayor announced Tuesday evening. 

"Everyone makes mistakes, including me, but what I can't allow is a breach of trust," Frey said in a press conference. "When you serve as chief of the Minneapolis Police Department, trust is not secondary to the job, it is the job. When trust is broken, it becomes extremely difficult to continue leading effectively." 

In a written reprimand to the police chief, Frey said an investigation into O'Hara's behavior found he interfered with a prior investigation that included allegations he had "engaged in sexual intimate relationships" with city employees. 

Frey said the investigation substantiated that O'Hara "knowingly and intentionally" deleted a contact card for a city employee from his city-issued cell phone during the original investigation, "in an attempt to shield that evidence" of his connection to the employee from investigators. 

"Although the investigators have concluded that the underlying allegations from the original investigation remain not substantiated, your interference with the investigation risked the integrity of the investigation and constitutes a significant breach of trust," Frey's reprimand to the chief said. 

Frey said Assistant Police Chief Katie Blackwell is the acting police chief effective immediately. 

Earlier this month, O'Hara was re-nominated as police chief by Frey, with the mayor saying, "he's the right leader for this moment." He was first sworn in as chief in November 2022, with one of his first priorities being rebuilding the ranks of the depleted police force. 

O'Hara is a New Jersey native. He started as an officer in Newark, served as public safety director, and was deputy mayor of Newark before taking the chief job in Minneapolis. 

The 47-year-old is married and has two children, who live on the East Coast.