Iowa state Sen. Kent Sorenson resigned Wednesday after a special investigator found probable cause that he violated the state’s ethic rules by taking money from committees tied to U.S. Rep. Michele Bachmann’s failed presidential campaign.

In a report filed with the Iowa Senate on Wednesday, independent counsel Mark Weinhardt found that Sorenson took money from two Bachmann political action committees by laundering the money through separate consulting firms.

Iowa Senate ethics rules prohibit legislators from receiving payment for work on political campaigns.

The money from the campaigns — the Bachmann for President committee and MichelePAC, a political action committee Bachmann created to raise money for other candidates — was accepted by Grassroots Strategies Inc., a company that Sorenson owns, Weinhardt found.

Sorenson served as Bachmann’s Iowa state campaign chair until late December 2011 when he left to work for former U.S. Rep. Ron Paul, just days before the 2012 Iowa Republican Caucus. Weinhardt’s report also found probable cause that Paul’s campaign paid Sorenson.

On two separate occasions, Sorenson issued written statements to the Senate Ethics Committee, denying that the Bachmann campaign paid him. He could face a felony charge because of the denial.

“We find probable cause to believe that those statements were false and that Senator Sorenson knew they were false when he made them,” the report said.

Bachmann has also denied the allegations that her campaign paid Sorenson.

The U.S. House Ethics Committee, Federal Election Commission, Federal Bureau of Investigation and U.S. Department of Justice are also investigating her presidential campaign. In an affidavit, former Bachmann chief of staff Andy Parrish revealed that Sorenson’s payments were routed through C&M Strategies, a company owned by Guy Short, who served as the national political director of Bachmann’s presidential campaign.

“Sorenson took the bulk of the money that C& M paid to GSI [Grassroots Strategies Inc.] as income for himself,” Weinhardt reported.

Weinhardt also investigated allegations that Sorenson and an associate stole an e-mail list of home school families from the personal computer of Barbara Heki, one of Bachmann’s Iowa campaign staffers. He did not find “clear and convincing evidence” that Sorenson committed a crime in connection with the theft.

Bachmann settled a lawsuit involving the matter. Terms of the settlement, reached in June, were not made public.

Corey Mitchell is a correspondent in the Star Tribune’s Washington Bureau. Twitter: @C_C_Mitchell