A Buxton man has been charged in federal court with posting social media threats that he wanted to “kill Jews.”

Brian Dennison, 24, faces one count of transmitting threatening interstate communication, a crime punishable by up to five years in prison. He appeared briefly in court Tuesday, when a judge ordered him temporarily detained until a hearing Thursday.

According to court documents filed in U.S. District Court in Portland, Dennison posted on Twitter on Sept. 8, “I’m going to kill jews with my ar15 tomorrow,” which triggered an FBI investigation. The threats were made on the second day of Rosh Hashanah, the Jewish new year.

Although Dennison posted using an anonymous Twitter handle, investigators were able to trace it to his email address, cellphone and an IP address.

Dennison has used the account to post or share other racist and xenophobic comments. He also posted on Sept. 8 that he was building a pipe bomb. The account was still active as of Tuesday, although the threatening posts have been deleted.

After tracing the Twitter posts, FBI task force officers obtained a search warrant for his residence, a garage apartment attached to his parents’ house on Fogg Road. Dennison, who works nights, was sleeping when officers arrived on Sept. 9, but when his parents woke him up, he refused to be interviewed, according to court documents.

Dennison’s parents did disclose that their son “had been obsessed with Jews for about three years and that he believed Jews were responsible for all of his problems.” The parents also told officers Dennison “never left the house unless he was going to work or to get food.”

His parents confirmed that Dennison turned over three handguns to officers after they visited the home but not an AR-15. The parents said they believed their son owned an AR-15 but they didn’t know where it was and Dennison did not answer questions.

Officer seized “large amounts” of ammunition from the apartment as well. There was no information in court documents about any bomb materials being recovered.

Dennison has been in custody since he was arrested on Sept. 11.