The civilian Los Angeles Police Commission has ruled that an LAPD officer's use of deadly force violated policy and the officer's account of the shooting wasn't credible.

The commission questioned Det. Arthur Gamboa's account of a shooting where he fired at a suspect who threatened the officer with a knife during an undercover drug buy, reports the Los Angeles Times.

During the buy, suspect Dale Garrett offered to sell Det. Gamboa a Klonopin pill for $5. After Garrett grabbed the marked bill, Det. Gamboa walked toward him. Garrent apparently turned, brandished a knife, and threatened to kill the detective.

Gamboa then fired two rounds that struck Garrett on the left side of his back and killed him. The commission cited the fact that Garrett was hit in the back as troublesome evidence, however research conducted by the Force Science Institute has indicated that subjects can be hit in the back while turning to run from an officer.

During an interview with POLICE Magazine in 2010, institute founder Bill Lewinski said it would take only about 14- to 16 one-hundredths of a second for a subject to turn from facing an officer to facing directly away from the officer.

"An officer firing at a cadence of a quarter second a round can shoot at the subject in the front and the next shot a quarter second later will hit that subject directly in the back of the head," Lewinski said.

Related:

The Force Scientist