A British Columbia man and former U.S. Army Ranger already serving time for armed robbery will spend an additional 20 years behind bars for trying to order a hit on a U.S. prosecutor – twice.

Luke Elliott Sommer, 23, of Peachland, was sentenced in U.S. District Court in Seattle Monday.

According to prosecutors, Sommer offered an undercover FBI task force agent as much as $20,000 for murdering an assistant U.S. Attorney in March 2009.

The propositions occurred barely a month into his sentence for masterminding the armed robbery of a Washington State bank branch.

Court documents show Sommer told the undercover officer he wanted media reports of the hit to reflect that the death was "murder, not an accident."

Two months earlier, Sommer used a home made knife to stab a co-defendant in the bank robbery case.

"There is no doubt that the defendant is a very dangerous man and needs to be locked up to protect society," said Assistant U.S. Attorney Gregory A. Gruber.

"This was an assault… on the heart of the criminal justice system."

Sommer was also handed a $25,000 fine.

During sentencing, he asked the judge to recommend a treaty transfer so he could serve his sentence in Canada.

Sommer was sentenced to 24 years in prison for his role in the dramatic robbery of a Tacoma Bank of America in 2006.

Clad in fatigues, Sommer led four men armed with automatic AK-47 machine guns and grenades into the facility and made off with more than $50,000 in cash. The men wore soft body armor in case of a police shoot out and carried hundreds of extra rounds of ammunition.

Twenty-three-year-old Tigra Robertson of Peachland, B.C., was sentenced to 12 years in U.S. prison for his part in the crime.

Sommer told others he wanted to use the proceeds to start a crime family large enough to rival the Hells Angels in British Columbia.

The men were quickly caught and arrested after an area resident noted the license plate of the getaway car.

Sommer, a duel citizen, served combat time in Iraq in 2004 and Afghanistan in 2005.

His mother, Christel Davidson, told CTV News her son was recently diagnosed with bipolar disorder -- and loves to develop grandiose plans.