TAMPA ó Police are bringing manslaughter charges against a Tampa man accused of throwing a fatal punch last April at well-known local muralist Matt Callahan.The suspect, 34-year-old Keith Mauga of Tampa, already is serving five years for aggravated battery in an attack on a St. Petersburg man. He was scheduled to be arrested in prison on the manslaughter charge.Police found Callahan in a median on Gandy Boulevard about 3 a.m. April 11, suffering from a head injury. Callahan died two days later at Tampa General Hospital.PREVIOUS: Reward offered for information in death of Tampa muralist Matt Callahan Callahan was 40 and left a wife and 5-year-old son. His murals appear on walls throughout the Tampa Bay area, at locations including the Lure restaurants in Tampa and St. Petersburg."The evidence against Mr. Mauga is compelling," Callahanís father Michael Callahan, a St. Petersburg lawyer, told the Tampa Bay Times on Tuesday. "I am extremely relieved that charges have finally been brought."New details about the night of the fatal encounter emerged in an affidavit filed with the manslaughter charge. Witnesses said Callahan and Mauga approached one another then walked away a number of times at the Warehouse Lounge on Gandy Boulevard, two blocks west of the Lee Roy Selmon Expressway entrance.It started when Callahan walked up to Mauga inside the bar and tried to apologize for an incident that occurred a few weeks before, according to the affidavit. Callahanís father has told the Times that tension between the two men stemmed from an earlier pool game.Mauga told Callahan again and again to leave him alone, and witnesses finally persuaded Callahan to leave the bar, the affidavit says.Around three minutes later, Mauga left the bar, too, and walked to the other side of the building where Callahan was sitting in his parked truck, the affidavit says. Mauga threatened Callahan and challenged him to leave the property and fight, witnesses told investigators. Callahan stayed in the truck and Mauga walked back around the building. About four minutes later, Callahan got out of the truck and walked toward Mauga. Four people intervened to keep Callahan away, the affidavit says.Mauga walk away, onto the median of West Gandy Boulevard. Callahan followed and approached Mauga from behind. Then Mauga turned and punched Callahan once, knocking him to the ground, according to the affidavit.Surveillance cameras at the bar and at a nearby gas station recorded part of the altercation. They showed Mauga walking away, leaving Callahan in the street.Callahan died from injuries he received when the back of his head hit the ground, according to the Hillsborough County Medical Examinerís Office. A witness later told investigators that two days after the incident, Mauga admitted to punching Callahan but said he did not mean to kill him.Mauga is serving prison time for an attack July 13 on Joshua Maville following an argument around the pool tables at the Sand Bar and Grill, 10056 Gandy Blvd., in St. Petersburg. As Maville was standing outside the business, Mauga ran up and punched him, according to court records.Maville fell and hit his head on the concrete, suffering injuries to his brain and face that required two days in a hospital. Contact Paul Guzzo at [email protected] Follow @PGuzzoTimes.