An owner of a Seattle medical marijuana dispensary has been sentenced to six years in prison after acknowledging his business was a front for illegal drug distribution and money laundering.

The U.S. attorney's office said 61-year-old Craig Dieffenbach was sentenced Friday. He pleaded guilty last August to federal charges of conspiracy to distribute marijuana and conspiracy to commit money laundering.

His Seattle Cannabis Cooperative was caught in a major state and federal crackdown on marijuana dispensaries in Washington state in November 2011. Co-defendant and dispensary co-owner Jing Jing Mo will be sentenced next month.

U.S. District Judge Marsha Pechman told Dieffenbach that he saw selling marijuana as a business opportunity rather than a way to help people.

Court records show Dieffenbach admitted operating two marijuana stores for profit, selling pound quantities to people who presented no medical authorization card.