A man arrested in Phoenix this week as part of an FBI terrorism investigation pledged support for Islamic State and researched “lone wolf” attacks online, according to court documents released Friday.

Derrick Thompson, 30 years old, was arrested Dec. 20 and is being held on suspicion of “participating in and assisting a criminal syndicate along with attempted misconduct involving weapons,” according to an FBI statement.

Michael DeLeon, FBI special agent in charge of the Phoenix division, said the investigation is ongoing and there are no indications of any additional threats associated with Mr. Thompson at this time.

The FBI’s Joint Terrorism Task Force had been tracking Mr. Thompson for more than two years.