A Waterville man has been indicted on federal charges he conspired with terrorists to plan a violent attack on a Shia mosque in the Chicago area and possessed homemade explosive devices.

A federal grand jury returned a two-count indictment Wednesday against Xavier Pelkey, 19, according to a statement Thursday from the United States Attorney’s Office for the District of Maine.

Pelkey intended to use explosives to commit “mass murder” at the mosque, according to authorities. Federal agents arrested Pelkey on Feb. 11 at his Front Street apartment in Waterville. He is being held behind bars until his case goes to trial.

Under the indictment, Pelkey is charged with conspiracy to provide material support to terrorists and possession of unregistered destructive devices, according to U.S. Attorney Darcie N. McElwee. The case was investigated by the FBI.

Law enforcement officials allege that between November 2021 and February 2022, Pelkey conspired with others to conduct the attack. The indictment alleges Pelkey possessed three homemade explosive devices when authorities searched his apartment Feb. 11. The devices were not registered to him in the National Firearms Registration and Transfer Record, authorities said.

Two juveniles who were communicating online with Pelkey told FBI agents, in a now-sealed declaration, of Pelkey’s alleged plan to use explosives to “commit mass murder” at a Chicago mosque, authorities have said.

If convicted, Pelkey faces up to 15 years in prison on the material support charge and 10 years in prison on the destructive device charge.