Republican gubernatorial candidate Ken Cuccinelli, left, greets Democratic challenger Terry McAuliffe during the Virginia Bar Association convention debate at the Homestead in Hot Springs, Va. on July 20. (Steve Helber/AP)

Attorney General Ken Cuccinelli II touts the role he played in launching a state investigation into Gov. Robert F. McDonnell in a TV ad released Thursday, the same day that Terry McAuliffe put out his own commercial criticizing Cuccinelli’s handling of a gas royalties case.

Cuccinelli, a Republican, and McAuliffe, the former Democratic National Committee chairman, are vying to succeed term-limited McDonnell as governor. Their latest ads underscore a theme both have pushed throughout the governor’s race: that their rival cannot be trusted.

Cuccinelli’s spot, titled “Facts,” also aims to put more distance between himself and McDonnell, the subject of state and federal investigations into luxury gifts and loans that a Virginia businessman provided to the governor and his family. Cuccinelli has his own ties to the businessman, Star Scientific chief executive Jonnie R. Williams Sr., but he also called on a state prosecutor to investigate the governor.

Williams provided $18,000 in gifts to Cuccinelli, who initially failed to disclose $4,500 of them as well as extensive stock holdings in Star. At the time, Cuccinelli’s office was representing the state in a civil tax suit brought by Star. Cuccinelli, who later had his office recused from the tax case, has said that the reporting lapses were oversights. A Richmond prosecutor reviewed the matter and found no evidence that Cuccinelli had broken the law.

As it seeks to squelch the notion of any Star-related wrongdoing, Cuccinelli’s ad also raises questions about McAuliffe and the electric car company he co-founded, which is the subject of a federal securities investigation related to how it sought foreign investors.

“There’s only one candidate under investigation: Terry McAuliffe,” Cuccinelli’s ad begins. “Potential fraud that killed jobs and threatened national security. And the press calls McAuliffe’s attacks false. A Democrat commonwealth attorney cleared Cuccinelli of any wrongdoing. Cuccinelli personally launched the investigation into Bob McDonnell. And called for immediate reform to strengthen ethics laws. Those are the facts.”

The Securities and Exchange Commission is examining how GreenTech Automotive and its sister company, Gulf Coast Funds Management, sought financing through the federal EB-5 visa program, which allows foreign investors to enter the country to create jobs.

McAuliffe, who quietly left GreenTech in December, has said he has no knowledge of the SEC inquiry. There is no indication that McAuliffe is personally under investigation.

“For an ad called ‘Facts,’ it omits quite a few about how Ken Cuccinelli accepted and then failed to report thousands of dollars in gifts, trips, and a $1,500 turkey dinner from Star Scientific and its CEO Jonnie Williams while their tax bill sat unpaid,” McAuliffe spokesman Josh Schwerin said. “Between his involvement in this major gifts scandal and the inspector general’s investigation of his office for helping out-of-state-energy companies over Virginia landowners, Ken Cuccinelli can’t hide the facts about his record of putting his own interests first.”

McAuliffe’s ad takes aim at Cuccinelli over his office’s handling of a mineral rights case, itself the subject of an investigation.

Virginia Inspector General Michael F. A. Morehart is probing allegations that a lawyer in the attorney general’s office improperly sided with out-of-state energy companies over residents in a dispute over mineral rights. Morehart’s investigation focuses on a Cuccinelli staffer, not Cuccinelli himself.

Titled “Paul,” the ad features Paul Osborne, a Southwest Virginia landowner.

“My family’s been in Southwest Virginia since the mid-1800s,” he says. “My grandfather would roll over in his grave if he saw what was going on today with the energy companies. Ken Cuccinelli is helping the energy companies take all that they can take from the landowners. He’s received over a hundred thousand dollars for his campaign. If I can’t trust him now as the attorney general, how am I going to trust him as a governor?”

The inspector general’s inquiry stems from a legal dispute between energy companies and landowners over which of them owns the rights to methane gas pumped from coal seams. Methane produced during mining operations used to be vented into the atmosphere, but advances in technology now allow it to be captured. Landowners who sold the rights to coal on their property before that technology was developed say they own the rights to the methane as well, while the companies say those rights belong to them.

The matter became in issue in the governor’s race in June, when a federal magistrate judge wrote that Senior Assistant Attorney General Sharon M.B. Pigeon had been “shockingly” involved in assisting the energy companies with their defense. One of the companies is part of a corporation that has given more than $111,000 to Cuccinelli’s gubernatorial campaign since 2010.

Cuccinelli has said that Pigeon communicated with company lawyers about the state’s Gas and Oil Act, which the companies are using in their defense and the commonwealth has an interest in protecting as existing state law.

“Ken has a long history of working for the people of Southwest Virginia, including offering legislation to release the gas royalties to the rightful owners and protecting the coal industry from the McAuliffe/Obama War on Coal,” Cuccinelli spokeswoman Anna Nix said via e-mail. “Ken will continue to campaign, in Southwest Virginia and across the Commonwealth, on his positive message of creating jobs, growing the economy, and easing the burden on middle-class families, while Terry apparently will do little outside lying about Ken’s record as well as his own.”