A Lethbridge senior is fighting for his life after police say he was assaulted while trying to stop a thief from stealing his bicycle.Police said the incident happened around noon on Wednesday along the 1200 block of 2 A Ave. North. The 80-year-old victim reportedly confronted a man who had stolen his bike from outside a business when the confrontation turned violent. The suspect allegedly punched the senior, knocking him to the ground where he struck his head on the pavement.The victim was taken to Chinook Regional Hospital before being airlifted to Calgary’s Foothills Hospital in critical condition with life-threatening injuries.Witnesses supplied photos of the suspect, allowing police to identify him quickly. After an extensive search, the 34-year-old man called dispatch around 8 p.m. to surrender. He was arrested without incident at a home on the city’s north side.Police say charges are pending and the investigation remains ongoing.