Camden, N.J. ? Surgery on Gov. Jon S. Corzine’s injured leg was successful Saturday, while state police said the driver blamed for the wreck that critically injured the governor told them he didn’t stop because he hadn’t realized he was involved.

The 20-year-old driver, whom police found the night after Thursday’s crash at an Atlantic City casino where he works, won’t be charged with leaving the scene of an accident, State Police Capt. Al Della Fave said.

Authorities left the door open for other charges to be filed, however, saying the investigation was not yet complete.

Corzine’s recovery was progressing better than doctors expected, said Dr. Steven Ross, head of trauma at Cooper University Hospital. Doctors cleaned a 6-inch wound during surgery on his left thigh.

The governor is not able to speak and not aware of his surroundings because of his heavy sedation. He is expected to remain on a ventilator until at least Monday, doctors said.

“He awakens, answers to simple ‘yes or no’ questions about pain,” Ross said. “He won’t remember much of what is going on at this point.”

Corzine was hurt Thursday when the SUV he was riding in was clipped by a vehicle that swerved to avoid a red pickup truck that officials said was being driven erratically. Corzine’s vehicle slammed into a guard rail along the Garden State Parkway in Galloway Township, near Atlantic City.

The driver of the red truck apparently thought he had avoided an accident because his vehicle never hit anything, police said.