James Jackson liked alt-right YouTube videos and boasted of high intelligence during his time in the U.S. Army before he killed a black man with a sword in New York this week.

Jackson, 28, was charged with second-degree murder Thursday after he took a bus from Baltimore to New York City with the express goal of murdering black men, according to prosecutors. Late Monday night, Jackson allegedly encountered Timothy Caughman, a 66-year-old black man he’d never met, and plunged a 26-inch sword into him. Prosecutors say the slaying just test run for a larger killing spree Jackson planned for Times Square.

“We are considering and expect additional charges on a grand jury level,” Assistant District Attorney Joan Illuzzi said in Thursday hearing. “This was an act, most likely, of terrorism.”

Police said Jackson confessed to the murder, to being a white supremacist, and to penning an anti-black manifesto, police said. Jackson also allegedly said he hated black men who were romantically involved with white women.

“The attack was clearly racially motivated,” NYPD Assistant Chief Bill Aubry said. “It’s well over 10 years he has been harboring these feelings of hate towards male blacks.”

But in the months before the attack, Jackson’s internet use suggested recent radicalization by the alt-right. Jackson’s YouTube page, where he had previously listened to the Final Fantasy soundtrack and liked a British royal family video, lit up with likes on videos about white superiority and “black on white crimes”.

The Daily Beast verified the YouTube account’s username as being associated with Jackson’s email address he listed on a résumé posted to his LinkedIn profile.

Jackson liked a livestream video called “Is It Time for Whites to Start Voicing Their Displeasure With Black on White Crimes?” two months before the attack. The two-hour video characterized African Americans as violent, and featured musical interludes of Donald Trump speeches set to electronic music.

“How many of you have got to the point where you’re more guiltless about your racism, or better yet your prejudice?” the livestreamer asked as viewers typed racial slurs in the comments.

Jackson also recently liked the videos “Blacks Know That Blacks Are Violent So Why Does the White Media Pretend They Are Not?” and “BLACK PERSON TALKS ABOUT ALT-RIGHT DESTROYED | MGTOW RED PILL SEXY TEEN CRINGE” and “Why I’m Quitting Porn & How to Achieve Any Goal & Cut Out Bad Behaviors.”

Jackson also subscribed to a series of racist channels including that of the National Policy Institute, a white-supremacist group founded by Richard Spencer. Another subscribed channel uploaded videos denying the Holocaust and claiming there are IQ differences between races. Videos in several other subscribed channels included “I Want a Fascist Ethnostate for Christmas” and uploaded broadcasts from Nazi website Stormfront.org and ex-Klansman David Duke. He also subscribed to the White House YouTube channel.

Jackson served in the U.S. Army from 2009 to 2012, leaving as a non-commissioned intelligence officer, according to the Department of Defense. His military record shows deployments in Germany and Afghanistan.

On his LinkedIn profile, Jackson claimed to have Top Secret/Secret Compartmentalized Information Security Clearance, one of the highest security clearances in the military, though it is not unusual for a soldier of his rank and position to have it.

Jackson also boasted of top-notch test scores: 97 out of 99 on the entry-level exam for the Armed Services. In one composite score of that exam, Jackson claimed a score of 141—a score of 110 is required to join special forces.

In Afghanistan, Jackson said he worked as an intelligence analyst in Kabul where he trained Afghan National Army intelligence officers.