A watchdog group has asked the US Senate to probe Las Vegas Sands chairman Sheldon Adelson’s ties to a Macau casino junket figure.

On Tuesday, the Campaign for Accountability (CfA) asked the Senate Committee on Homeland Security and Governmental Affairs and the Federal Election Commission to investigate Sands and Adelson’s ties to Chinese crime groups.

Specifically, the CfA wants to know if “illegally laundered foreign funds” make up some of Adelson’s notoriously large Republican campaign contributions. US laws prohibit foreigners from contributing to US election campaigns and CfA Executive Director Anne Weismann says the American people have a right to know if “triad money is winding up in the campaign coffers of U.S. politicians through Mr. Adelson’s contributions.”

The CfA singles out Sands’ business ties to Cheung Chi Tai, who, according to varying accounts, either was or still is a prime figure in the Neptune Group junket operation. A couple decades ago, a US Senate committee fingered Cheung as the leader of a Hong Kong triad group. Cheung is currently facing charges of money laundering in Hong Kong related to his junket activity.