Those special counsel investigations do have a way of producing results where one might least expect it.

Take the probe being conducted by Robert Mueller into the “Russia thing,” whether the Donald Trump presidential campaign colluded with Russians who were hacking into our electoral process in 2016.

It turns out that Mueller has enlisted the aid of Internal Revenue Services criminal investigative team to help him in his investigation of the Russia matter.

Why is this so, um, titillating?

The president told us when he launched his campaign two years ago that the IRS was conducting a “routine audit,” which prevented him from releasing his tax returns for public view; presidential candidates of both parties have been releasing their returns every election year dating back to 1976.

Trump has vowed to release them; then he backed away from that; then he sort of said he would release them; now he’s apparently back to the “no way” mode regarding the returns.

The IRS involvement is important to Mueller reportedly because it could reveal whether Trump had any business interests in Russia, something he denies. Evidence is piling up that Trump, uh, more than likely lied about that.

What needs saying once again is that a routine audit does not prevent release of the returns, according to the IRS. Moreover, Trump never has produced a shred evidence that the IRS is actually auditing his tax returns; he’s presumed that we should take his word for it.

The tax returns are important for a number of reasons. They shed light on the nation’s top public official’s business connections; they will tell us if the president really is as rich as he kept bragging he is; in this instance, they’ll reveal whether Trump is truthful about having “no business dealings in Russia.”

The tax return issue won’t go away. Nor should it. Not until the president keeps faith with a four-decade political tradition and releases them for full public scrutiny.