A former Missouri police officer has pleaded not guilty to federal charges accusing him of excessive force when he used his stun gun on a teenager last year.

Timothy Runnels was arraigned Friday in Kansas City, Missouri, on two counts apiece of deprivation of civil rights and of obstruction of justice in connection with the September traffic-stop encounter with 17-year-old Bryce Masters. Runnels is free on bond.

A federal indictment alleges the former officer in the Kansas City suburb of Independence "continuously" shocked Masters with his stun gun while the teen already was on the ground and unthreatening, then dropped Masters face-first onto the ground while he was restrained.

The teen's heart stopped, but he survived.

Runnels' attorney, J.R. Hobbs, declined on Friday to publicly discuss the charges.