The Philadelphia District Attorney's office has asked the city's police department to compile more evidence in the case involving a shooting outside Marvin Harrison's car wash in North Philadelphia on April 29, according to a report on ESPN.com. Detectives are still trying to piece together what happened, relying on ballistics tests and information from witnesses and two victims that have been less than fully cooperative. "We don't approve charges unless we can prove them in court," said an official with the district attorney's office.