Despite preliminary information that shows the shooting of a suspect by a Hamilton County sheriff's deputy was accidental, a thorough investigation must occur, Sheriff Jim Hammond said.

Deputy Mike Thompson, a narcotics officer with the department for at least five years, is on administrative leave during the investigation, said sheriff's spokeswoman Janice Atkinson.

Thompson was carrying an assault rifle Wednesday as he entered an apartment at 7301 East Brainerd Road. He and other deputies were serving a warrant for drug charges on 22-year-old Cecil Vance.

When Thompson was entering the second-floor apartment, he tripped, firing one round from his rifle and striking Vance in the left leg. Vance was taken to a local hospital with a wound that wasn't life-threatening, Atkinson said.

Deputies who are issued assault rifles are trained with the weapon and must qualify in its use just as they are with the department-issued pistol, Hammond said. Use of weapons depends chiefly on the decision of each operation's supervisor, he said.

"Supervisors make this call in what we call a pre-raid when they look over the evidence they have, what they're likely to encounter when they move in on that call," Hammond said.

Department procedure dictates that an officer will disengage the weapon's safety when ready to move in, he said.

"You don't want to disengage it after the firing starts," he said.

In Thompson's case, internal affairs officers will investigate how each phase was of the operation was handled, the sheriff said.

"Was this a timely call for the use of this firearm?" Hammond asked. "Internal affairs will review each and every step to make sure everything was done properly."

Hammond said Vance and the other apartment resident, Samantha Heather Cronin, 22, would be taken into custody on charges of felony possession of drug paraphernalia, manufacturing marijuana and simple possession of marijuana.

Neither Vance nor Cronin was listed in court records or jail booking reports as of Thursday night.