Parkland School Shooting Suspect: Portrait of an Angry Young Man With an AR-15

Who is Nikolas Cruz, the accused school shooter in Florida?

After 17 students and teachers were shot to death at a Florida high school Wednesday, questions have once again arisen about the motives of an angry young man with a semi-automatic weapon.

Nikolas Cruz, 19, the accused shooter, had a troublesome history of loving guns and knives, according to his social media posts. He had been expelled from Marjory Stoneman Douglas High School last year after reportedly fighting with his ex-girlfriend's new beau.

His internet posts about wanting to grow up to be a school shooter caught the attention of social media users and the FBI was contacted, but agents could not track down the person who posted them, according to reports.

He returned to the high school on Wednesday and pulled a fire alarm, hoping to lure more targets into his shooting path, authorities said.

Cruz was an orphan and had been living with a friend's parents. His adoptive mother died of pneumonia in November. Her husband died of a heart attack in 2004.

They were described as a loving family who adopted late in life when they moved to Florida.

Cruz’s former classmates described him as a loner who cursed at teachers and was prone to outbursts.

His Instagram account, now deleted, showed photos of him with a handgun and wielding knives between his fingers.

He had a legally purchased AR-15 semi-automatic rifle when he moved in with his friend’s family. The parents ordered him to keep the weapon in a locked gun box.

He was taking high school equivalency classes, but had stayed home Wednesday, sleeping in and reportedly telling his guardians, “It’s Valentine’s Day, and I don’t go to school on Valentine’s Day."

By 2:30 p.m., he was opening fire at his old high school, according to authorities.