Just two and a half months before 19-year-old Nikolas Cruz took an AR-15 to his former high school and killed 17 people, it was revealed that he put a gun to the head of his half-brother, Zachary. 

During a chilling 911 call to local authorities, Cruz’s neighbor, who was responsible for the suspect and his brother after the death of their mother, said he had “used a gun against people before,” reported WPTV.

After his mother died from flu complication in November, Cruz began acting violent shortly toward his younger brother Zachary (Nikolas and Zachary are pictured holding their mother’s ashes in a photo published by the Daily Mail).

Although the two had just moved into neighbor Rocxanne Deschamps’ trailer home, Cruz’s violent behavior was immediately noticed.

According to a report, Cruz and Deschamps’ 22-year-old son, Rock, had fought.

“He came in the house and started banging all the doors, and banging all the walls. Hitting the walls, throwing everything in the room, and then my son got in there,” Deschamps told Palm Beach County dispatchers.

During a different incident, Deschamps reported that Cruz had threatened her son Rock with a shotgun. In the 911 call, she revealed that Cruz had put guns to the head of his brother and mother.

“He put the gun to the head of his brother before. This is not the first time, and he did that to his mom, and his mom died. It is not the first time that he put a gun on somebody’s head,” she told dispatchers.

The day before the altercation between Rock and Cruz, a social worker from Marjory Stoneman Douglas High School asked deputies to check on Zachary Cruz, WPTV reported.

Since his mother died, the then 17-year-old boy hadn’t shown up at school but “was never disenrolled from school in Broward to attend any other school,” the social worker said.

Deputies visited the trailer but were told to come back later. It’s unclear if they did.

Last Friday, Zachary was involuntarily committed to a mental facility. He turned 18 on Wednesday.