Online forums and social media have continued to serve as vital tools for spreading racist ideologies, misinformation, conspiracies and hate. It's led to the rapid radicalization of people like the alleged Buffalo shooter, Payton Gendron, according to an ABC News analysis of what authorities have identified as Gendron's writing.

"The online environment serves terrorists in several very valuable ways," said Daniel Byman, a professor at Georgetown University and a senior fellow at Brookings Institute. "It gives them very easy reach. Ideas kind of ricochet around the world very rapidly and people can form communities around the world."

Gendron said he was radicalized in recent years after engaging with white supremacists online, according to a document authorities say details his plans and motives that has been reviewed by ABC News.

These documents show Gendron self-radicalizing when the pandemic began, spending inordinate amounts of time reading hate posts on social media, a senior law enforcement source briefed on the case told ABC News.

In the months and weeks leading up to his alleged attack on the Buffalo supermarket mass shooting, he became increasingly violent in tone on online platforms, according to the source.

In the document allegedly detailing his plans for attack, he expressed racist and antisemitic sentiments and declared white supremacist conspiracies as his motive behind the attack.

"Violent extremists are increasingly using social media for the distribution of propaganda, recruitment, target selection, and incitement to violence," FBI officials Michael C. McGarrity and Calvin A. Shivers said in a 2019 statement to the House Oversight Committee during a hearing on white supremacy.

[abcnews.go.com]