Sen. Chuck Grassley wants to know what the Securities and Exchange Commission did with complaints it received about potential improper trading by Steve Cohen’s SAC Capital.

But Grassley’s request that the SEC provide an official accounting for its actions seems a bit odd, given that securities regulators recently settled an insider trading case with former SAC Capital analyst Jonathan Hollander.

With federal prosecutors continuing to look into allegations of improper trading at Cohen’s fund, it’s hard to make the argument that SAC Capital hasn’t been investigated. Indeed, Reuters first reported in December 2009, that as far back as 2007 FBI agents have been looking into allegations of improper trading at SAC Capital.

But none of that has deterred the Iowa Republican from asking the SEC to provide an explanation of how regulators responded to 20 separate referrals of potential improper trading over the past decade. Grassley said he wants “to understand how effectively the SEC pursues referrals such as these” from the Financial Industry Regulatory Authority and other sources.

But here’s a bit of irony: SEC Chairman Mary Schapiro, to whom Grassley addressed his letter, was the head of FINRA for much of the time that those referrals about SAC Capital were made to the SEC.