The former owner of half a dozen L.A.-area medical marijuana dispensaries was sentenced Monday to six years in federal prison for conspiring to sell the drug, officials said.

Virgil Edward Grant II, 42, of Carson pleaded guilty last June to a single conspiracy count after federal agents raided the dispensaries, which authorities claimed were operated like retail pot stores.

The federal investigation began after a driver who was high on marijuana crashed his pickup truck into a car that had been stopped by a CHP officer, authorities said. The crash resulted in the death of the driver of the stopped vehicle and left the CHP officer paralyzed, officials said.

Investigators later determined that the driver of the pickup had purchased marijuana and "marijuana edibles" from one of Grant's dispensaries, Holistic Caregivers, in Compton.

At Monday's hearing, U.S. District Judge Stephen V. Wilson labeled as "not credible" Grant's explanation that he was operating his multiple marijuana dispensaries as nonprofit cooperatives. According to federal prosecutors, Grants' facilities generated more than $1.3 million in revenue during more than two years in business.Grant has been in federal custody since December, when authorities shut down the dispensaries he was continuing to operate, said a spokesman for the U.S. attorney's office. His six-year sentence is to be followed by three years of supervised release.

Federal authorities dropped charges against his wife, Psytra Monique Grant, 33. A former employee, Stanley Jerome Cole, received probation in the case.