German police have released two men taken into custody on Monday for questioning about last month's nail bombing in Cologne that injured 22 people, authorities said on Tuesday. The two suspects were released after a few hours of questioning after police said they didn't have enough evidence to hold them any longer. The two men are believed to be connected with a 23-year old German who was questioned on the weekend but also released for lack of evidence. Police said the 23-year old appeared to be the man seen on footage from a video surveillance camera pushing a bicycle toward the scene shortly before the nail bomb exploded. Investigators have yet to establish a motive for the attack, but believe it was most likely related to ordinary criminality, and not terrorism.