JEFFERSON COUNTY, Colo. -- A man has been sentenced to prison for attacking and robbing an 81-year-old man in the restroom of a Westminster movie theater, authorities said Thursday.

Jeffrey Sang Knouse, 40, was sentenced to six years in prison, followed by five years on parole. In August, a jury found Knouse guilty of seven felony counts, including robbery of an at-risk adult and identity theft.

In June 2010, Arthur Maes, 81, was standing at the urinal in the restroom at the Westminster Promenade movie complex when Knouse attacked him from behind, said district attorney spokeswoman Pam Russell.

Maes was using a cane for balance, and Knouse shoved him, knocking him to the ground, police said. Knouse grabbed his wallet and ran.

After the assault, police publicized a surveillance video taken at a nearby store. It showed Knouse using the victim's credit card eight minutes after the attack.

Police received an anonymous tip that led to Knouse's arrest in November 2010.

Knouse told police that he had targeted Maes because he was elderly and used a cane, Russell said.

The arrest was a relief for Maes, who had told police that, after the attack, he had been scared to go to the movies or go out with his wife.

District Attorney Scott Storey said it's this kind crime that motivated him to create an Elder Abuse Unit in February 2010. He stressed that crimes against seniors require special training and resources.

“It is fortunate that Mr. Maes was not more seriously injured and that his identity was not seriously compromised," Storey said. "The elderly are often at greater risk of victimization than others in our community.

"My office is committed to protecting them. Those who prey on the vulnerability of seniors in Jefferson and Gilpin counties will be held accountable," Storey said.