FORT WORTH — A dispute over the proceeds from a lawnmower sale sparked the fatal assault on a homeless man Sunday, police said.John William Gifford, 45, was being held in the Mansfield jail Friday with bail set at $100,000 in the case. He faces a charge of murder in the death of Kevin Giguere, 55.Police believe the assault took place about 10 a.m. Sunday morning in an alley behind the 1300 block of Denver Avenue.Homicide Sgt. Joe Loughman said Gifford and Giguere had sold a lawnmower together. A fight over the proceeds apparently sparked a physical altercation between the two homeless men that led to Giguere's death, he said.Loughman declined to identify the type of weapon investigators believe was used in the assault.He said Giguere remained conscious after the assault but lost consciousness that night, prompting his friends to call 911. Police arriving at the service station in the 800 block of Northside Drive found a witness giving CPR to Giguere.He was taken by ambulance to Texas Health Harris Methodist Hospital Fort Worth, where he pronounced dead the next morning.Gifford was arrested on a murder warrant at a residence int he 1600 block of Denver Avenue about 10:30 a.m. Thursday, Loughman said.