A Mendocino County biologist was arraigned Tuesday in San Francisco federal court on charges alleging he conspired with a Yurok tribal member to embezzle more than $800,000 in federal grant funding intended for environmental studies.

Ron LeValley, of Little River, entered a not guilty plea to the charges against him, according to court documents.

The Yurok tribal member who initiated the alleged scheme, Roland Leroy Raymond, has admitted to spending the money on drugs and gambling, according to federal court documents.

Raymond has pleaded guilty to one count of conspiring to embezzle the funds from his tribe while he was its forestry director. He is scheduled to be sentenced next week.

LeValley and his attorney, William Kimball, said they cannot comment on the case at this time. Raymond's attorney could not be reached for comment.

The case revolves around the apparent misuse of federal grant funds obtained for Endangered Species Act biological assessments on Yurok tribal land in Del Norte and Humboldt counties.

According to court records, Raymond convinced LeValley and others at Mad River Biologists, a consulting firm based in Eureka, to submit dozens of invoices to the tribe for environmental assessments they had not performed. Raymond misled LeValley, saying he needed the money for timber clearing and other fire prevention work that was needed but for which there was no funding, according to court documents. Raymond also told LeValley he wanted to give bonuses to Mad River Biologists and the fire crews, according to court records.

Instead of hiring timber crews, Raymond spent the money he received on drugs and gambling, according to court records. He is undergoing drug rehabilitation treatment but tested positive for methamphetamine as recently as September, according to court records.

The embezzlement scheme began in 2007 and ended in 2010, according to court records.

Mad River consultants normally would submit invoices and Raymond would approve them. Mad River Biologists then funneled most of the money back to Raymond when the invoices were paid, according to court documents.

Raymond also prepared and submitted many of the invoices himself, according to court records.

The scheme came to a halt only after a co-conspirator pressured Raymond to stop and refused to continue funneling money back to him, according to court records. They did not name the co-conspirator.

LeValley is also a photographer and was a member of the Marine Life Protection Act science advisory team for the North Coast.

The embezzlement of federal funds designated for tribal uses is common, according to a recent survey by the Associated Press.

American Indian tribes have been caught misappropriating tens of millions of taxpayer dollars, according to the study, based on internal tribal audits and other documents. Serious concerns have been raised about 124 of 551 tribal governments, schools and housing authorities that received at least 10 years of substantial federal funds since 1997, the report states.

The federal government does little to combat the problem, the study found.

Embezzlement cases in general also have plagued tribes.

In Mendocino County, federal authorities charged eight tribal leaders from the Coyote Valley reservation north of Ukiah with misusing tribal funds in 2004. But the massive case fizzled five years later and the only two defendants remaining in the case pleaded guilty to failing to file tax returns.