LOCKPORT – Ricky Q. Caldwell, of Niagara Falls, who has been to state prison three times, is headed back after pleading guilty to attempted third-degree robbery Monday in Niagara County Court.

Caldwell, 48, of Michigan Avenue, admitted to the charge in connection with a theft attempt May 6 at a Family Dollar store on Hyde Park Boulevard in the Falls.

Police said Caldwell loaded up two bags of merchandise and pulled a knife on a clerk who tried to prevent him from leaving the store. He faces mandatory prison time of up to four years when he returns before County Judge Sara Sheldon Farkas on Aug. 26. In the meantime, he’s being held in lieu of $50,000 bail.

Caldwell’s criminal resume includes 27 months in prison for a 1983 first-degree sexual abuse conviction; 30 months behind bars for a 1991 attempted third-degree robbery plea; five years, starting in 1998, for fifth-degree criminal sale of a controlled substance; and 32 months in prison after a 2005 plea to attempted third-degree burglary.