SAN FRANCISCO -- A member of the Mongols motorcycle gang was sentenced to life in prison today for murdering the president of the San Francisco Hells Angels.

Christopher Bryan Ablett, also known as "Stoney," was sentenced to serve two concurrent life sentences and one life sentence to run consecutive, according to U.S. Attorney Melinda Haag.

Ablett is committed the gang-related murder of Mark "Papa" Guardado, the president of the San Francisco Chapter of the Hells Angels in San Francisco on Sept. 2, 2008.

"The defendant killed a complete stranger for no reason other than his membership in a rival motorcycle gang," Haag stated.

The Mongols are an organized criminal motorcycle gang who are rivals to the Hells Angels motorcycle gang, say officials.

During Ablett's trial, the evidence showed that Ablett was armed with a foot-long military knife and a .357 magnum revolver when he went to visit a friend.

When Guardado learned that Ablett was wearing a Mongols patch shirt in a bar in Mission, Guardado went to the street outside the bar and approached Ablett, according to Haag.

A fight broke out and Ablett stabbed Guardado four times and shot him twice, killing him.

The jury rejected Ablett's claims that he acted in self-defense and found that Ablett murdered Guardado to increase his status in the Mongols, according to Haag.