DETROIT — Detroit Police Chief Ralph Godbee Jr. has retired effective immediately amid a scandal involving his relationship with a female officer in the department, Mayor Dave Bing announced at a news conference Monday morning.

Bing said he met with Godbee on Sunday. He said he did not force Godbee to resign, but said it had become clear the chief had to step down.

Assistant Chief Chester Logan will serve as interim chief.

“I think this was the right decision by the chief and therefore I support it,” Bing said.

Bing said he had gotten to know Godbee well and respected him as a leader.

“It bothers, hurts me a great deal that it has come to this,” Bing said. “I worry about him as a person and hope that he’ll be able to get on with his life no longer as part of the Detroit Police Department, but as a citizen of Detroit.”

Bing suspended Godbee for 30 days last week after allegations the chief was having an affair with Angelica Robinson, who works for the department in internal affairs. Robinson’s gun was taken away after she became distraught and posted a photo of herself with a gun in her mouth on a social networking site. She was evaluated by a doctor and was cleared to return to work with her gun, a department spokeswoman said Friday.

When asked if Godbee admitted to a relationship with an internal affairs officer, Bing said: “He did tell me that he had a relationship with Ms. Robinson, yes.”

Bing said Godbee was embarrassed.

“He felt he had let me down. He felt he had let the department down. He felt he had let the citizens of Detroit down,” Bing said.

The chief, who is married, filed for divorce in August. He has declined to comment.

His retirement letter, dated Monday, makes no mention of the affair or what led to his stepping down. Instead, it opines about his career in the department, which he began working for in 1987, and his gratitude for being able to serve the city.

“I retire proud of the fact that I was able to assist during a time in which our city has most been in need and I thank Mayor Bing and his administration for allowing me Godbee replaced former Detroit Police Chief Warren Evans. Bing fired Evans, who also was accused of having a relationship with a subordinate.

Soon after Godbee was appointed, it was revealed he also had had a relationship with the lieutenant Evans was dating.

He said Godbee, at the time, was the right choice.

“At the time of my selection, I think I made the right decision,” Bing said.

The mayor said he spoke with Godbee during his tenure about his behavior because of the prior indiscretion with the lieutenant.

“We have had that conversation on more than one occasion because I had concerns just based on the history, and he confided in me that he had changed his ways,” Bing said. “And I had no reason not to believe that.”

Bing said he told Godbee what his expectations were.

“He didn’t live up to those expectations,” Bing said, “and that leads us to where we are today.”