Newly Released Footage Shows Nikolas Cruz Doing Target Practice in a Backyard

Newly released footage of Nikolas Cruz, the 19-year-old who killed 17 people in a high school shooting on Wednesday, has been uncovered showing him firing off a BB gun in his backyard.

The video was taken by a neighbor, and shows Cruz holding the gun while wearing boxer shorts and a red "Make America Great Again" hat.

Cruz had posted photos to his social media accounts of himself showing off an assortment of guns and knives.

On Wednesday, Cruz entered Marjory Stoneman Douglas High School in Parkland, Florida and opened fire inside the building wielding an AR-15 semi-automatic rifle. He killed 14 students and three adults, while injuring more than a dozen others.

Cruz was taken in by a student's family after his adoptive mother Lynda died of pneumonia in November. The family said they were aware he had the AR-15 rifle, but had never seen him use it.

"It was in a locked gun safe. That was the condition when he came into their home, that the gun was locked away," Jim Lewis, the family's lawyer, told ABC News. "They're hurt and shocked. They're just like everybody else, trying to make some sense of this and trying to figure out why."

The New York Times reported on Wednesday that when living with her, Lynda Cruz had to call the police to come to their home and calm down Nikolas several times.

"I think she wanted to scare them a little bit," Helen Pasciolla, the Cruz family's neighbor, told the paper. "Nikolas has behavioral problems, I think, but I never thought he would be violent."

Cruz was expelled from Douglas High School during the 2017 school year for "disciplinary reasons," according to the police. One of the teachers on staff told The Miami Herald on Wednesday that Cruz was not allowed on the school grounds following his departure.

"We were told last year that he wasn't allowed on campus with a backpack on him," Jim Gard said.. "There were problems with him last year threatening students, and I guess he was asked to leave campus."

Cruz was arrested within hours of the shooting and confessed to killing the 17 people during the initial interrogation. He was charged with 17 counts of premeditated murder on Thursday.