Federal prosecutors have added charges against a Detroit-area man who was captured in Syria and accused of providing support to the Islamic State group.

Ibraheem Musaibli is charged with conspiring to provide material support to IS, firing a machine gun and receiving military training. The government says Musaibli was captured by the U.S.-backed Syrian Democratic Forces last summer and flown to the U.S. He first appeared in court in July .

U.S. Attorney Matthew Schneider says the new charges, filed Tuesday, "more fully capture" Musaibli's alleged conduct while overseas. If convicted, he faces at least 40 years in prison.

A message seeking comment was left for his attorney.

Musaibli's relatives say he isn't an IS fighter. They say the 28-year-old U.S. citizen was in Syria to work and study religion.