The House Committee on Homeland Security on Tuesday requested the current owner of the site 8chan to testify in front of Congress after investigators discovered that the suspected El Paso gunman may have posted a hate-filled screed on 8chan shortly before allegedly killing 22 people in a shooting spree on Saturday.

Committee chair Bennie Thompson (D-MS) and ranking member Mike Rogers (R-AL) sent the site owner, Jim Watkins, a letter detailing their concern over not only the El Paso shooter’s alleged manifesto on the “Hispanic invasion,” but also the fact that the New Zealand mosque shooter and the Southern California synagogue shooter had both posted white nationalist ravings on 8chan before carrying out deadly acts of violence this year.

“Americans deserve to know what, if anything, you, as the owner and operator, are doing to address the proliferation of extremist content on 8chan,” Thompson and Rogers wrote. “To that end, the Committee on Homeland Security respectfully requests your presence to provide testimony regarding 8chan’s efforts to investigate and mitigate the proliferation of extremist content, including white supremacist content, on your website.”

8chan was taken offline on Monday after its internet host Cloudflare terminated its agreement with the site for “refusing to moderate their hate-filled community.”

Watkins denied that the suspected El Paso shooter had posted a manifesto on the site. Prior to the shooting, Watkins said he doesn’t “have a problem with white supremacists” using his site as a platform.

“They have reasons for their beliefs,” he told Splinter in April. “I don’t need to justify their reasons.”

The original founder and former owner of 8chan, Fredrick Brennan, told the New York Times on Sunday that the site needed to be shut down in wake of the El Paso shooting.

“It’s not doing the world any good,” Brennan said. “It’s a complete negative to everybody except the users that are there.”