ELK GROVE VILLAGE, Ill. (WLS) -- Federal charges have been filed against a man in the shooting of a U.S. postal worker on New Year's Eve in Elk Grove Village.Cameron Ruebusch is accused of opening fire on a U.S postal employee who was delivering mail near his home in Elk Grove Village.According to a complaint and affidavit, Ruebusch is charged with "assaulting an agent of the United States government..."Ruebusch allegedly approached 36-year-old Stephen Casazza's unmarked postal vehicle, tapped on the window, and according to the complaint said "What's up man?" Investigators said when Casazza looked over he saw a handgun and immediately drove away.As Casazza was driving away, prosecutors said Ruebusch opened fire. Casazza was shot multiple times in the back, chest and arms and is now recovering in the hospital.Neighbors came out to help Casazza and his father is grateful his son is alive."Unbelievable," said Stephen J. Casazza, Sr., the victim's father. "He is incredibly lucky, and I hope he realizes that God gave him another chance."Ruebusch has been arrested multiple times in the past. He has a history of drug and assault charges.Police said multiple witnesses identified him in the shooting. Police also said that he may have tried to hide the gun in nearby Busse Woods Forest Preserve.Authorities are still not offering a motive in this case. If convicted, Ruebusch could face 20 years in prison.Meanwhile, Casazza's father says his son has no idea why he was shot and that he has a long recovery ahead of him.