Updated

The founder of a Northern California medical marijuana training school said Friday he was giving up his downtown Oakland-based pot businesses after a federal raid bankrupted him.

Richard Lee has been instrumental in pushing for ballot measures to legalize the drug, giving more than $1.5 million as the lead financial backer of a 2010 initiative to legalize the drug in the state.

He said he will now focus solely on his advocacy work.

"I am now in this legal situation, so it's better for me to step aside," Lee said.

Internal Revenue Service and Drug Enforcement Administration agents on Monday raided Oaksterdam University, Lee's home and a medical marijuana dispensary he also founded. The purpose of the raids hasn't been disclosed.

Oaksterdam University offers classes to would-be medical marijuana providers in fields ranging from horticulture to business to the legal ins-and-outs of running a dispensary. It does not distribute marijuana.

Agents confiscated marijuana, computers and files from Lee's businesses, making it difficult to continue operations, he said. The university has held some classes since the raid and is soliciting donations to stay up and running. Oaksterdam Executive Chancellor Dale Sky Jones is working to put together a new leadership team for the school, he said.

Lee said the agents who came to his home Monday morning showed him search warrants but did not tell him what they were seeking or the purpose of their investigation.

"It was something we've always feared, but we've always known it's a part of the politics of this issue," Lee said.

Federal prosecutors in San Francisco, who have been leading a months-long crackdown on medical marijuana dispensaries, did not immediately return messages seeking comment. Lee said he was not interrogated but simply detained while the agents conducted the raids. He was not arrested.

Lee said his decision to step back from the businesses was not part of any deal with investigators "We don't know if it will make any difference at all to them," he said.