Four months before Del City police Capt. Randy Trent Harrison shot and killed Dane Garrett Scott Jr., he arrested Scott for reportedly selling drugs near Del City High School.

Now two years later, Harrison's first-degree manslaughter trial in the man's death begins in Oklahoma County District Court.

Harrison, 48, faces a first-degree manslaughter charge in the March 14, 2012, shooting death of Scott, 18, of Del City, an unarmed man shot in the back after a car chase that ended in Oklahoma City.

The case is a rare instance of a law officer being charged in an officer-involved shooting, and some of his supporters say his actions were proper and that the case could set a dangerous precedent.