RIVERSIDE (CBS) — A man who helped his roommate set up a series of bizarre booby traps against Hemet police was back behind bars on Tuesday.

KNX 1070′s Brian Ping reports the 20-year prison sentence for Steven Hansen could have potentially been a lot longer.

Hansen, 38, of Homeland, plead guilty on Monday to helping Nicholas Smit attempt to fire a World War II-era bazooka rocket at the Hemet police department building.

The rocket ultimately failed to fire after the launcher was later determined to be a training device.

Hansen, who was paroled just three months before the botched attack, accepted a deal that may have saved him from a life sentence.

Smit was sentenced to four consecutive life terms in December for orchestrating the attacks, which also included a failed pipe bombing and a gas explosion setup that was snuffed out.

He was said to have targeted a Hemet police officer in revenge for a past arrest on drug charges.

No injuries were reported in any of the attacks.