Over his teenage years, Dustin Brown, of Morton, pursued interests with fixations driven by autism — aviation, child pornography and, eventually, mass murder.

The latter two led Brown, 20, to the 32-year prison sentence he received Wednesday for possessing child porn, then trying to kill an elderly man who thwarted his knife-wielding assault on a room full of children at the Morton Public Library last year.

Brown’s mental conditions, including an intellect years behind his age, and sexual abuse he said he suffered as a child may have contributed to his actions, but he understood they were criminal, his judge said in his sentence hearing.

The public needs to be protected from someone “who commits fairly horrific crimes” that stem from twisted fixations that will remain difficult to control, said Tazewell County Circuit Judge Paul Gilfillan.

Time served since Brown’s library assault and good behavior could reduce his prison term to about 22 years. He’ll receive mental health therapy during that time. 

Brown, however, could remain incarcerated for years more under state law if he’s designated a sexually dangerous predator.

He pleaded guilty but mentally ill last month to possessing child porn, attempted murder and armed violence. 

The latter two charges stemmed from his attack Oct. 13, 2015, on James Vernon in a library conference room where Vernon was tutoring about 17 children in a chess club meeting.

Vernon, then 75, used old Army knife training to stop Brown, who entered the room shouting, “I’m going to kill some people!” The children and several parents escaped as Vernon, despite a severe wound to his hand, subdued Brown. 

He targeted the children when he saw them in the library, where he had gone to pursue his plans to kill people with two large knives he’d brought in his book bag. Those plans grew from a fixation over mass killings he’d developed while watching video games, Gilfillan heard.

Brown told police the children sparked a desire for revenge after he was charged eight months earlier with possessing more than 200 computer-downloaded videos and pictures of pre-teen girls engaging in sexual acts. He was free on bond when he sought to kill in the library.

“I want to thank you for saving my life” that day, Brown told Vernon during a break in his sentence hearing.

In comments to Gilfillan, he apologized to “the victims I viewed” in the porn videos. “They were hurt and abused,” he said, just as he allegedly was as a child.

Brown’s parents testified they had no idea until after Brown’s arrest on the porn charges that, according to Brown’s account, he was sexually abused for a half-dozen years by his older brother, who’s now imprisoned on an unrelated sex-related case. The parents had adopted the boys as young children.

Assistant State’s Attorney Kevin Johnson sought a total 50-year sentence in the cases. Brown’s attorney, Michael Doubet, asked for their minimum 16-year term.

Follow Michael Smothers at Twitter.com/msmotherspekin