A 57-year-old man was arrested in the Bayview district Saturday for the alleged murder of his nephew, whose body was discovered by police the day before inside a Visitacion Valley home.Broderick Douglas of San Francisco is alleged to have killed his 24-year-old nephew Marcus Douglas, who police found suffering severe head trauma at 5:08 p.m. in a residence on the 1500 block of Sunnydale Avenue. The medical examiner ruled Marcus’ death a homicide. Police were able to track down Broderick based on witness statements and other evidence, but Officer Grace Gatpandan could not disclose further information on the investigation. A possible suspect was said to have fled the area in a red vehicle. Broderick was arrested on the 1400 block of Palou Avenue and booked on murder at County Jail. The homicide marks the 19th of the year and fourth of 2015 in the immediate area of the Crocker Amazon Playground. In late March, a man was shot and killed on the other side of the park at Geneva Avenue and Moscow Streets. Less than a month earlier, two teenagers were gunned down while sitting in a car in the playground’s parking lot.