Dennis Libby, who confessed to holding up a clerk at knife point at the Sierra Trading Post in Pioneer last August 25, was sentenced to two years in state prison Tuesday, according to District Attorney Todd Riebe. Libby was charged with second degree robbery with a deadly weapon. Libby entered the store wearing a mask and holding a large kitchen knife. He gave the clerk a note demanding money from the cash register and instructions to place the money into a bag.  Libby then fled on foot with $282. Amador County Sheriff’s office began an investigation which ultimately led detectives to Libby at his residence less than ½ mile from the Trading Post.  Libby admitted committing the robbery to Sheriff’s detectives Tom Rayzor and Lieutenant Drew Stidger. At the time, Libby said his motive for robbery was financial hardship.