A Casper man is heading to prison after admitting he used an airsoft gun to rob a business.

Forty-four year old Steven Knox was sentenced to five-to-eight years in prison after he pleaded guilty to one charge of aggravated robbery.

Prosecutors say in middle June, a visibly drunken Knox revealed a handgun and threatened the life of a store employee, while in a checkout line at the east-side Casper WalMart.

He then walked off with more than $430 in merchandise, but not before a number of witness saw what he did.

Knox then used the butt of his gun to break through the locked glass door on the west side of the store and then took off running.

Police found him a short time later at the First Interstate Hotel.

During the investigation, police found an empty airsoft gun box in the store’s housewares department.

A breathalyzer showed that Knox had a blood alcohol content of .12, and Knox advised the nursing staff at the Natrona County Detention Center, that he took five CC’s of heroin earlier that night.