A Loudoun County deputy was found guilty Tuesday of assaulting a handcuffed man in his custody.

John Wayne Gregory, a 10-year Sheriff’s Office veteran who has been on paid administrative leave since the investigation began into the June 14 incident, was fined $500.

His attorney, Caleb Kershner, immediately appealed the case to Loudoun County Circuit Court.

District Court Judge Norman deVere Morrison handed down the verdict after a two-hour trial.

According to the testimony, the case began when Sgt. Brett Philips was waved down by a woman in front of Mighty Mike’s Bar and Grill in Sterling. She said she was worried about an inebriated man sitting in a pickup in the parking lot. Philips found Lyle Murphy Grenoble slumped behind the wheel of the truck, in a condition described as obviously intoxicated and possibly passed out.

Grenoble said he was waiting for a roommate to pick him up. The keys were not in the ignition. As Philips pressed him for information on when his friend would show up, Grenoble became agitated and then aggressive. Gregory joined Philips on the scene as his supervisor made the decision to arrest Grenoble, charging him with public intoxication.

He was handcuffed and placed in the back of Gregory’s cruiser. Grenoble became more agitated as he waited for officers to complete the search of his pickup, complaining frequently that the cuffs were too tight.

The altercation happened in the secure garage at the Loudoun Adult Detention Center in Leesburg. When Gregory opened the door to let Grenoble, who was still handcuffed, get out, the two stood together and then the deputy suddenly forced the suspect to the ground on his back and held his head down with his hand, shouting.

Grenoble said he wasn’t sure what happened or why. “I was in a bit of a daze because my head hit the asphalt,” he said.

Gregory said he felt Grenoble push his body toward him and feared he was about to be attacked. The take-down maneuver was an instinctive action that came from years of training, Gregory said.

The key evidence in the case was the surveillance videos recorded from several angles inside the ADC unloading area. In particular, is the audio that helped sway Morrison toward a guilty verdict.

Gregory is heard yelling, “You want to square off on me again? I will [expletive] you up.”

The deputy apologized repeatedly during the trial for cursing. “I felt like I was going to be harmed,” he said.

Judge Morrison said he felt Gregory overreacted and could have stepped back from the encounter.

He said there was no question that Genoble was acting like an “arrogant, obnoxious drunk,” but said he saw no aggressive move toward the deputy before Gregory pinned him to the ground. And the judge said he was disturbed by the deputy’s language.

Even if Gregory feared an attack, Morrison questioned whether the deputy had no more right than an average citizen to make an anticipatory strike. “I think Deputy Gregory overacted,” he said.

Contacted after Tuesday’s trial, Sheriff Mike Chapman said it was always sad when a law enforcement officer faces criminal charges. Chapman said he initiated the investigation after reviewing the security recordings, describing the incident as “very disturbing.”

He sent the case to Commonwealth’s Attorney James Plowman, who referred it to Fauquier County prosecutor Paul R. Walther. The assault charge was brought following an investigation by the Virginia State Police, although Gregory was not interviewed by the investigating trooper.

A hearing on Gregory’s Circuit Court appeal had not yet been set Tuesday.

Chapman said Gregory would remain on administrative leave.

Contact Norman K. Styer at nstyer@loudounnow.com.