A University of Southern California student stabbed another man to death this week after he was caught breaking into a car outside an off-campus fraternity house.

That USC student, Ivan Gallegos, 19, will not face criminal charges after prosecutors determined that he acted justifiably in self-defense, local affiliate KNBC reported Friday.

Prosecutors believed the claims of Gallegos and other witnesses that he acted reasonably out of "genuine fear" for the safety of himself and others after the car burglar, a homeless man named Xavier Cerf, 27, falsely claimed he had a gun and reached for his waistband.

Car break-in leads to stabbing death

KNBC reported separately on Thursday that the Los Angeles District Attorney's Office said, "After careful consideration and a thorough review of all available evidence, we have decided not to pursue charges against USC student Ivan Gallegos."

"We believe that Mr. Gallegos’s actions were driven by a genuine fear for his life and the lives of others. Our heart goes out to the deceased’s family, friends, and everyone impacted by this tragic incident," the DA's office added.

According to CBS News, the deadly incident occurred around 8:15 pm Monday when Gallegos and two others heard a car alarm going off and went to investigate -- Gallegos armed with a knife, one of his friends with a large stick -- following a string of car burglaries and violent crimes in the area.

Surveillance video showed Cerf was caught in the act of burglarizing a car and initially refused demands to exit the vehicle, though he eventually got out and claimed to have a gun as he reached for his waistband. Gallegos rushed him at that point and used one hand to grab the suspects hands and the other to stab him once in the chest, then stabbed him three more times as a struggle ensued.

The police were called immediately and Cerf, who had been unarmed, was found dead near the scene. Gallegos had waited for authorities at the scene, was cooperative and detained without incident, and was held in custody on a $2 million bond for several days. He claimed that he had acted in self-defense because he sincerely believed that Cerf was reaching for a weapon he claimed to have.

DA's office agrees deadly force was "proportionate and objectively reasonable"

Local affiliate KABC reported Thursday that L.A. County DA George Gascon said in a statement, "There is consistency in the assessment that the decedent indicated he had a gun. Although he didn't have a gun, he did reach out for his waistband."

"When you look at the totality of the circumstances, it really indicates there was a reasonable belief, that Mr Gallegos believed his life was in danger," the DA added.

A document filed by the DA's office stated, "The use of deadly force under these circumstances was both proportionate and objectively reasonable and would support a claim of perfect self-defense. Filing is rejected."

Lawyer says student "did exactly what he was supposed to do"

Mark Geragos, the attorney representing Gallegos, told KNBC, "This is a terrifying situation. What do you do in a situation like this? I think Ivan did exactly what he was supposed to do, which was to try to stop a crime. Unfortunately, the person he tried to stop it with escalated the matter and that’s where he found himself."

The deceased, Cerf, was described by the outlet as an "unhoused" individual who'd moved to southern California from Texas earlier in the year and had a string of prior arrests and misdemeanor charges on his record.

Cerf's mother, Yema Jones, insisted her son was innocent and doing nothing wrong, revealed that he had just been released from a mental hospital earlier that day, and questioned the need for him to be stabbed to death by the USC student.