Watkins posted a video on his YouTube channel on Tuesday, saying the manifesto was first published on Instagram and not on his site. He said the document was then uploaded to his site by another user and that law enforcement had been “made aware” of it.

“First of all, the El Paso shooter posted on Instagram, not 8chan,” Watkins said. “Later, someone uploaded the manifesto. However, that manifesto was not uploaded by the Walmart shooter. I don’t know if he wrote it or not, but it was not uploaded by the murderer that is clear.”

Facebook, which owns Instagram, said in a statement, “We have found nothing that supports this theory.”

A spokeswoman for the company said it disabled an account tied to the suspected gunman on Saturday but the account hasn’t been active in more than a year. The social network is currently working with law enforcement and directed any additional questions to the Federal Bureau of Investigation. The FBI declined to comment on Watkins’ statement.