The two met at the Alpha and Omega Christian Church in Southwest Miami-Dade, where Boria is an ordained minister. A pastor introduced the men about three years ago, Boria said.

But they only became close in the past few months, the mayor said. Recently, Carollo has joined the Borias for lunch at the family home, has sat in on the mayor’s media interviews and has kept track of his schedule.

Carollo’s new position marks his latest foray into South Florida politics. He served as a sharp-spoken Miami commissioner in the 1980s. He lost a 1997 Miami mayoral bid to Xavier Suarez, but then became mayor after successfully arguing in court the election was tainted by ballot fraud.

His four years as Miami mayor were rocky. He had bitter disputes with then-commissioners Tomás Regalado and Arthur Teele Jr. At one point, Teele and Carollo got into a physical confrontation at Miami City Hall as a meeting was taking place.

Carollo lost his reelection bid in 2001. He was arrested shortly before leaving office for throwing a cardboard tea box at the head of his wife Mari, police said. The charges were dropped and the two have since divorced.

Despite the controversies, Carollo gained recognition for helping to pull Miami out of a $68 million budget hole. And he was not implicated during one of Miami’s darkest scandals, Operation Greenpalm, which sent several city officials to prison in a bribery scheme.

It was Carollo who had suggested to Boria the city hire Stierheim as interim city manager — an endorsement that Carollo now calls an “embarrassment” and a “regret.”

“I recommended this man,’’ he said. “I brought this man here and I feel very responsible for what has happened here. So I felt I had a responsibility to come and help at this time.”