A tipster identified Green as the shooter several days after the killing, according to the Post. When detectives learned Green was on house arrest, they asked the city Pretrial Services Agency for his whereabouts on the day of the shooting. The GPS tracker showed he was at home, police said -- and remained there days later. Investigators checked camera footage from the area near the shooting and spotted a gunman with an obvious limp, according to FoxDC. Inside Green's home, police with a search warrant discovered a box in his living room containing the prosthetic leg with the tracking device still attached to the ankle.