The FBI foiled a possible domestic terrorist attack against a Jewish temple, arresting an anti-Semitic and Nazi-sympathizing white supremacist who allegedly plotted to firebomb Colorado’s second-oldest synagogue, according to court documents released on Monday.

Richard Holzer, 27, was arrested following a monthlong sting operation. A Boulder, Colorado, resident and self-described skinhead, Holzer made openly racist comments and violent threats online and detailed his intentions to shut down the Temple Emanuel in a plot that escalated from poisoning to using Molotov cocktails and even pipe bombs and dynamite to demolish the building, authorities said.