Federal authorities in Colorado have arrested a man they accused of plotting to blow up a synagogue in Pueblo, a city two hours south of Denver, according to federal court documents.

The man, identified as Richard Holzer, 27, used several Facebook accounts to promote violence and show support for the Holocaust, writing in July in a private message, for example, that he was “getting ready to cap people,” the documents said.

The message included a picture of him aiming a long gun while dressed in clothing displaying white supremacy symbols. He told another Facebook user, “I wish the Holocaust really did happen” and, speaking of Jews, “they need to die.”