It wasn't too long ago when Ohio Republicans were rocked by systemic scandals, which led then-Gov. Bob Taft (R) to face criminal conviction and even sent then-Rep. Bob Ney (R) to prison.

We haven't seen controversies of this magnitude since, and the stench of corruption didn't dissuade Ohio voters from giving the GOP big victories in 2010, but there's a burgeoning scandal in the Buckeye State that's causing some heartburn in Ohio Republican circles.

At issue are questionable donations, first reported by Alec MacGillis, which went to Ohio Treasurer Josh Mandel (R), who's running for the U.S. Senate this year, and Rep. Jim Renacci (R), who's in a competitive race of his own. The suspect contributions have already drawn the interest of federal law enforcement officials.

The Toledo Blade argued today that Mandel, in particular, has some explaining to do.

The most recent questionable -- but unanswered -- incident involves more than $100,000 in donations to the Mandel campaign from the owner and 16 employees of Canton-based direct marketer Suarez Corp. A Blade investigation last year revealed that at least some of the donors and their spouses gave the legal maximum amount of $20,000 total to Mr. Mandel and U.S. Rep. Jim Renacci (R., Wadsworth).

Owner Benjamin Suarez, a backer of Republican causes, says that the Mandel campaign solicited the donations and that his workers are well paid. But records suggest that at least some of the donors are of unusually modest means to contribute that much money to political campaigns. The FBI apparently agrees, and is investigating the donations.

Though details of the FBI probe are not yet available, it is illegal for a company to reimburse employees for campaign contributions. Whether that happened in this case is unclear, but when workers of modest means, who do not have a history of writing large campaign checks, suddenly donate the maximum to their boss' preferred candidates, it's enough to raise some eyebrows.

Mandel returned the money last week and acknowledged that he's aware of the FBI investigation. He also struggled when asked by a local reporter about the suspect donations, as evidenced in the video posted above.

Apparently, if the Republican writes thank-you notes, that clears up the controversy?

In his original report, MacGillis chatted with some of the folks who made some of the dubious contributions.

In a more upscale neighborhood not far away, I found Charles Stewart, the director of merchandising at Suarez, who had given Renacci only $250. He was setting out in his car with a woman whom I presumed to be his wife. I asked why so many Suarez employees were giving to the two candidates. "The owner of our company is very Republican," he said. But, he added, "He doesn't push the executives to give." Then he said something that piqued my interest: "There was an investigation. I wasn't involved in it, because I didn't give the amount of money [others] gave." The woman tugged on his arm, urging him to shut up. He apologized, saying he had to go and that his mind was a bit jet-lagged. [...]

I visited the home of Michael Blubaugh, a copywriter at Suarez who had given $5,000 each to Renacci and Mandel last year -- and whose wife, Donna, had done the same. They live in a modest subdivision, in a home valued by Zillow at about $142,000. When Donna came to the door, she said she had already been asked about the donations by the FBI. The inquiry had caught her by surprise, she said, "because I didn't know about the rules, so I was like, 'What?'" But she said the $20,000 had been given of her and her husband's free wills. "Our house may not look it, because we're saving for retirement, but my husband makes good money as a copywriter," she said. But why give so much to the candidates? "My husband made the decision, not me," she said.

The donations have also caught the attention of the U.S. Attorney's office in Cleveland, which has asked Mandel's and Renacci's offices for more information.

To be sure, we don't yet know for sure whether the donations were illegal, and what role, if any, the Republican officials had in the matter. At a minimum, though, it's a story worth watching.