NOONDAY, Texas (AP) -- William Krar and Judith Bruey assembled a frightening arsenal in three rented storage units in this East Texas town, and federal authorities are trying to figure out why.

A raid in April found nearly two pounds of a cyanide compound and other chemicals that could create enough poisonous gas to kill everyone inside a space as large as a big-chain bookstore or a small-town civic center.

Authorities also discovered nearly half a million rounds of ammunition, more than 60 pipe bombs, machine guns, silencers and remote-controlled bombs disguised as briefcases, plus pamphlets on how to make chemical weapons, and anti-Semitic, anti-black and anti-government books.

The findings have led to one of the most extensive domestic-terrorism investigations since the 1995 Oklahoma City bombing.

In 1985, Krar was arrested in New Hampshire for impersonating a law enforcement officer, according to the FBI. He stopped paying federal income taxes in 1989. His ties to New Hampshire's white supremacist and anti-government militia groups in the mid-1990s were investigated by federal agents.