BOZEMAN, Mont. – Elizabeth Clare Prophet, the spiritual leader of the Church Universal and Triumphant, which gained notoriety in the late 1980s for its followers’ elaborate preparations for nuclear Armageddon, has died. She was 70.

Prophet suffered from advanced Alzheimer’s disease for years, and was at her apartment when she died Thursday night, said legal guardian Murray Steinman. Steinman said he was not aware of any other complicating health issues.

Prophet led the Park County church that once boasted 50,000 members. In the late 1980s, church members amassed assault rifles and armored vehicles in preparation for a nuclear missile strike that Prophet predicted was on the way. The plan brought national notoriety and a federal investigation.

The church’s beliefs combined icons from the world’s major religions, mixing Western philosophy and mysticism. Despite her disease, videos and writings of Prophet continued to dominate church teaching, transformed into a New Age publishing enterprise and spiritual university.

The church was still prepared for Armageddon in recent years and kept a bomb shelter stocked for 750 people deep in a forest near Yellowstone National Park.