SIOUX CENTER, Iowa (AP) — A former northwest Iowa fifth-grade teacher charged with multiple acts of sex abuse and released on bond last November is back behind bars on new charges. Sioux City television station KTIV reports that 36-year old Curtis Van Dam was arrested Friday morning at his Sioux Center home on a federal warrant charging him with sexual exploitation of a child and possession of child pornography.

Van Dam has already pleaded not guilty to 146 Iowa counts, including 73 counts of second-degree sexual abuse. His trial on the state charges is set to for March 6. Police say the charges stem from incidents involving numerous children over four years and that the crimes occurred at various locations, including Sioux Center Christian School, where Van Dam worked.