An off-duty Natrona County Sheriff's deputy helped arrest a Casper man whom he reportedly saw pleasuring himself outside a convenience store not far from downtown Casper on Wednesday.

Gerritt Joseph Shepperson, 61, was booked into jail on a charge of public indecency. He'll likely make his initial appearance at 2 p.m. in Natrona County Circuit Court.

Charging papers say at about 4:20 p.m., police officers responded to the area of Fifth and Wolcott after being told an off-duty deputy was following a man -- Shepperson -- who had allegedly been touching himself while watching a woman sitting outside.

Shepperson was arrested, though he claimed to have been heading to a nearby apartment building to install a smoke detector.

The deputy told officers he had stopped at the Loaf and Jug at the intersection of Poplar and Collins. As he walked back out of the store to his personal vehicle, the deputy passed a white Ford F-150, in which he saw Shepperson with his pants and underwear down around his knees, with his shirt pulled over his groin area. Shepperson appeared to be pleasuring himself while watching a female Loaf N Jug employee.

The deputy told Shepperson to stop and get out of the car. Shepperson responded by saying he had an "accident" and was "changing," though the deputy saw no other clothing in the truck.

Shepperson then pulled out of the parking lot and headed east on Collins, driving 30-35 mph in the 20-mph speed zone in front of Natrona County High School. The deputy followed, and ultimately found Shepperson's truck in the parking lot east of an apartment building on East Fifth Street.

Shepperson was reportedly walking across the parking lot toward the building, carrying a long screwdriver and a smoke detector.

The deputy got out, identified himself and told Shepperson to stop. Shepperson reportedly refused several orders from the deputy, so the deputy took Shepperson to the ground and held him there until police showed up.

Shepperson reportedly told responding officers that he had an "accident" and had been changing his underwear in front of the convenience store before going to install the smoke detector at the apartment building.

He denied having touched himself, but said he had "been caught before." When asked to explain what he had been caught doing, Shepperson allegedly admitted he had previously been caught pleasuring himself, though he was not sure on how many occasions.