The University of Southern California (USC) student who police said fatally stabbed a homeless man he witnessed trying to break into cars on Greek Row will not face charges, the Los Angeles District Attorney announced on Thursday.

L.A. DA George Gascón declined to file charges against Ivan Gallegos, 19, who was arrested after Xavier Cerf, 27, was stabbed to death on Monday, June 17.

"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," Gascón's office said in a statement to Fox News Digital.

The LAPD received a call on Monday night after two of Gallegos' peers reportedly witnessed Cerf trying to break into multiple cars. 

USC STUDENT ARRESTED IN STABBING DEATH OF SUSPECT ATTEMPTING CAR BREAK-IN

The three USC students then confronted Cerf and the situation escalated.

During the altercation, Gallegos allegedly stabbed Cerf, who suffered serious injuries.

Police found Cerf in the walkway between two fraternity houses in the University Park neighborhood in Los Angeles when he collapsed. Officials said he was pronounced dead at the scene.

ONE DEAD AT USC AFTER WITNESS STABS SUSPECT ATTEMPTING A CAR BREAK-IN: POLICE

Police said Gallegos stayed at the scene and cooperated with them. He told police he acted in self-defense. 

Gallegos was initially arrested on suspicion of murder, Fox 11 previously reported. He had no criminal record and his bail was set at $2 million.

Gascón's office said further details about the investigation will be released at a later time.

Fox News Digital's Landon Mion contributed to this report.