Here’s another sign of how radioactive Benghazi is becoming.

Benghazi committee Chair Trey Gowdy (R-SC) is now returning $6,000 in political donations that are indirectly tied to a PAC that ran a nasty anti-Hillary Clinton ad showing the grave of the U.S. ambassador killed in the 2012 attacks, the Washington Post reported Monday.

Gowdy is coughing up the money after the paper inquired about ties between Gowdy and Dan Backer, who used to serve as treasurer for Gowdy’s now-defunct leadership PAC. Backer is now the treasurer of the The Stop Hillary PAC, which aired the ad that flashed images of all four Americans killed in the Benghazi attacks in addition to Ambassador Chris Stevens’ grave, during the first Democratic presidential primary debate last week.

“I’d like to hear why you tried to silence the Benghazi whistleblower,” the ad’s narrator said. “But Mrs. Clinton, I can’t. What difference does it make?”

The donations Gowdy is returning actually come from three other PACs where Backer serves as treasurer. Gowdy received $2,000 each from the Conservative Action Fund, Special Operations Speaks PAC and Tea Party Leadership Fund on the same day in May, according to the report.

After the Post inquired about Gowdy’s ties to Stop Hillary PAC, Benghazi committee spokesman Jamal Ware told the newspaper that those three donations were returned Friday. He added that Gowdy had refused donations this summer from the Stop Hillary PAC and another Backer-linked PAC.

“The memories of our lost fellow citizens should not be used for fundraising, nor should their families’ suffering be exploited,” Ware told the Post. “If you hear Trey Gowdy, Benghazi and donate in the same message, Mr. Gowdy would personally encourage you to ignore the request.”