State authorities are investigating whether Marin County Supervisor Kate Sears violated anti-corruption laws by supporting millions of dollars in public contracts for Shell Energy North America while owning a small fortune in its stock.

The investigation by the California Fair Political Practices Commission has the potential to lead to criminal charges by local prosecutors. The Marin County District Attorney’s Office has asked the commission to send its findings for review.

The investigation is based on a complaint by Novato resident Jim Phelps, an energy consultant and longtime critic of MCE, formerly known as Marin Clean Energy. Sears has spent several years on the MCE board and is now the chair.

The power authority buys electricity from renewable sources for the stated purpose of reducing greenhouse gas emissions.

“While holding stock in Royal Dutch Shell, Sears voted to approve extending a multi-million dollar contract with Shell Energy North America, a subsidiary of Royal Dutch Shell,” the complaint alleges, according to an FPPC notification letter. “Sears also executed a separate sole source $5 million contract with Shell.”

The $5 million contract refers to a three-year deal in 2014 for power generated at a hydroelectric dam on the Columbia River. Sears signed the contract along with Dawn Weisz, the chief executive officer of MCE.

Sears owns $10,001 to $100,000 in Royal Dutch Shell stock, according her FPPC financial disclosure forms. She also owns stock in numerous other oil companies, Pacific Gas and Electric, and corporations in the pharmaceutical, tech, consumer goods and financial sectors.

Phelps, in an interview, said the petroleum company holdings are “kind of an in-your-face to all of Marin County.”

“Someone who professes to be heading a clean energy company, what are you doing with all these oil stocks?” he said.

Phelps said he has “not yet” filed complaints against any of the other Marin public officials on the MCE board. He said he is doing additional research.

Sears said, “I am cooperating with the FPPC to resolve the matter.”

She declined to answer a question on whether the stocks are lumped into a relatively passive investment such as an index fund or retirement account. However, the FPPC generally does not require public officials to report those kinds of accounts.

Supervisor Damon Connolly of San Rafael, who has also signed off on MCE expenditures while sitting as board president, has listed no reportable economic interests with the FPPC.

Sears, who represents Southern Marin as the District 3 supervisor, was appointed to the seat by Gov. Jerry Brown in 2011. She won election in 2012 and re-election in 2016.

She is a graduate of Harvard Law School and used to work in the consumer law section of the California Attorney General’s Office.

Jay Wierenga, spokesman for the Fair Political Practices Commission, declined to comment on the specifics of the Sears case, but he said the time frames for investigations vary. The most recent analysis by the commission determined that about two-thirds of cases are completed within 180 days and 90 percent within a year.

Penalties can range from a warning letter to $5,000 per violation, he said.

The FPPC receives more than 1,000 complaints a year, ranging from allegations of campaign violations to public corruption. A majority of complaints never reach a full investigation stage.

From April 6 through May 11, for example, the enforcement division received 70 complaints and opened 11 investigations, according to a staff report.

“A matter will be fully investigated if there is sufficient information to believe that a violation of the (Political Reform) Act has occurred,” the commission’s website says.

The commission notified the Marin County District Attorney’s Office that it wanted to open an investigation into Sears. District Attorney Ed Berberian said he asked for the results of the inquiry to determine if any criminal provisions of the Political Reform Act were violated. His office is not conducting a parallel investigation.

MCE serves Marin County, Napa County, Richmond, Benicia, El Cerrito, San Pablo, Walnut Creek and Lafayette.

Weisz, the chief executive, said it would be premature to comment on the FPPC inquiry at this stage in the process.