http://www.msnbc.msn.com/id/38597704/ns/us_news-crime_and_courts/ By Mike Brunker Projects Team editor msnbc.com updated 8/7/2010 1:16:27 PM ET The already shorthanded police department in Flint, Mich., has a big problem on its hands a serial killer who is roaming the streets at night and randomly and repeatedly knifing lone men he encounters. At least 13 men all but one African-Americans have been stabbed repeatedly by a young, muscular white man since mid-May, and five of them have died from their wounds, according to police in the financially strapped auto manufacturing city. Ten of the attacks have occurred in Flint, with the other three taking place in nearby townships. The Michigan State Police released a sketch of the attacker on Friday a lightly goateed man shown wearing a white T-shirt and baseball cap and sporting a stud in his left ear. City officials have not labeled the attacks as racial in nature, though they say that there does appear to be a pattern in the selection of victims, the Detroit Free Press reported Friday. In addition to being black, most of the victims have been old, disabled, small of stature or otherwise vulnerable, it said. Flint police said the victims were all outside alone at night. Survivors have said the attacker approached them under the pretense of needing directions or help with a broken-down vehicle. "He then pulls a knife and attacks them without saying anything more," Flint police Lt. T.P Johnson told The Associated Press on Friday. Detectives have been investigating the attacks since they started, but a pattern only became apparent on Tuesday, a day after 49-year-old Arnold Minor was found slain along a Flint street, Johnson said. That led to the announcement that a serial killer might be on the prowl in the working-class city ravaged by economic turmoil, budget problems and police layoffs.