A University of Southern California student will not be charged in the fatal stabbing of a suspected car burglar near campus, prosecutors said Thursday.

Ivan Gallegos, 19, of Los Angeles, was booked into jail on suspicion of murder early Tuesday and held on $2 million bail following the Monday night attack, police said.

The victim, Xavier Cerf, 27, was pronounced dead at the scene — an alley behind USC’s Greek Row — shortly after the Monday evening confrontation, according to the DA’s office and the county medical examiner.

A charge evaluation worksheet produced by the DA’s office concluded that the student should not be charged, mainly because he was acting in self-defense after he and two others said they heard the man say he had a gun.

“We believe that Mr. Gallegos’s actions were driven by a genuine fear for his life and the lives of others,” District Attorney George Gascón said in a statement Thursday.

USC spokesperson Lauren Bartlett said Tuesday that Gallegos was enrolled as a junior studying business administration.

The evaluation said Gallegos was at a fraternity house where he lives when he and two others heard a car alarm activate at the rear of the property, which faces an alley, about 8 p.m. Monday.

They went to investigate because there had been a string of car break-ins, the evaluation said. Gallegos had a knife and another witness had a stick, it said.

They found the victim inside a 2010 Mercedes-Benz associated with the house, it said. When confronted, Cerf told the three that the vehicle had been calling to him, the document states.

The evaluation said the victim was homeless.

The man began to step out of the vehicle, and when Gallegos confronted him, he said he had a gun, the evaluation said. All three of the students who had gone to investigate the break-in said they heard the man say he had a gun, it said.

The evaluation states that that two of three called 911 and said a man with a gun who was breaking into cars had been injured in a stabbing.

Gallegos said the victim started to reach for his waist so he used his left hand to grab the suspect’s hands, believing he may have been trying to grab a gun, and stabbed him with his right hand, the evaluation said. He stabbed him three more times during a physical struggle, the document states.

He and the two companions returned to the house to wait for officers, it said. The evaluation said there was no indication the victim had a gun.

Jail records indicate Gallegos was arrested about a half hour after officers arrived. He was released at 12:22 p.m. Thursday, according to the jail.

The victim’s mother, Yema Jones, told NBC Los Angeles he was a dancer and comedian who moved to L.A. from Texas. He was recently hospitalized for 20 days for an unspecified mental health ailment and had been released the day of his death. “I’m lost. I’m confused. I’m hurt,” she said.