Sanford police are investigating an attempted armed robbery Tuesday night at a local motel, where the perpetrator was seen on a surveillance camera waving a knife. Sgt. Craig Andersen said in a news release that a man entered the Super 8 Motel at 1892 Main St. around 8:24 p.m. and demanded that the desk clerk hand over money. The suspect leaned across the front desk and showed a silver-bladed knife in his right hand.