Criminal/gangland slang, to shoot, or kill.
Cf. Robert B. Parker Double Deuce (1992):
"We used to standing around," Major said. "Stand around a lot. Stand around sell some sub. Stand around pick up some wiggle, stand around throat a little beverage. Maybe trace somebody."
"Trace?" I said.
Major grinned. "You know, line sombody, haul out you nine and..." With his thumb and forefinger he mimicked shooting a handgun.
"Ah," I said. "Of course."
Possibly derived from the chalk outline marking the location of a body at a crime scene.