ANCHORAGE — The instant you lay eyes on the guy, you know exactly how Sherman “Tank” Jones got the nickname. The resemblance is remarkable.

With the body of a bulldozer and head like a wrecking ball — let’s just say you’d be ill advised to diss his mama.

Yet a big part of his job requires being invisible. Him and his size-15 alligator shoes.

As a private investigator, Tank Jones sees what isn’t meant to be seen, hears what isn’t meant to be heard, knows what is supposed to be secret. He’s pretty sure, for example, that a client’s boyfriend who ducked out the door at 5:30 for an early-morning run didn’t mean to be videotaped indulging in a little side-dish activity on top of a picnic table in Anchorage’s Elderberry Park.

“In the beginning, I used to say, ‘I can’t believe they did that,’” Jones said. “I don’t say that anymore.”

After 47 years on this planet, and more than 20 years as a “private eye,” there’s one thing Jones is absolutely certain of: Love can make people really, really stupid.

With a degree in criminal justice from the University of Alaska, Jones has a day job doing criminal and civil investigations, mostly for defense attorney Rex Butler. The fooling-around stuff, he does on the side.

“Is YOUR partner, husband or wife CHEATING?” hollers the ad he runs in the Anchorage Press. “Having an AFFAIR or FLING? Let us uncover the truth. Tank Jones Investigations: Discreet, confidential.”

Suspicious boyfriends, girlfriends, husbands and wives keep this man busy.

“Right now,” he says, “I can’t hardly keep up with the demand.”

Jones charges $65 to $175 an hour, with those higher rates kicking in once he has to travel outside the Anchorage area, stay in motels and rack up other expenses.

Before taking a case, he says, he asks potential clients why they’re suspicious, why they don’t just come out and ask. Sometimes, he’ll give suggestions on how to gather evidence on their own.

If they decide to hire him anyway, he’ll make an appointment for a consultation. More often than he likes, once they sit down and start talking, there’s no shutting them up.

“People go into their sex lives deeper than … it’s more than I want to know,” Jones said.

Judging strictly from his caseload, women cheat more than men, and they’re harder to catch.

“I’m gonna tell you something, doing this for over 20 years, women are very, very good. Oh, yeah. Men, we don’t have a clue. We’re too busy beating our chest like King Kong.”

Men cook up the dumbest excuses too. Like the guy who claimed his affair with an old girlfriend was for charitable purposes, to keep her from committing suicide.

And the lamest lies: That man seen with another woman? “Wasn’t me, just someone who looks exactly like me.”

Cheats and liars

In a shared office at Butler’s Anchorage law firm, dressed in a sleek gold suit, a diamond pinkie ring the size of a postage stamp and a gold watch so big it would take him straight to the bottom should he fall in the Inlet, Jones ran through a few of his more memorable cases:

The suspicious bride-to-be who learned her fiance had a boyfriend.

The traveling husband who found out his wife didn’t have a boyfriend after all. She had three.

All this exposure to the tawdry side of love takes a toll on one’s personal life. Jones is single, and he thinks that’s for the best.

“You know, if I got into a relationship, I probably would investigate that person,” he said. “I probably have. Now, I won’t admit whether I have or not. But I probably would, and that’s not good.”

When doing infidelity work, Jones may pull the old hidden-camera-in-the-baseball-cap trick. Or the situation may require a stakeout, sitting with cameras ready in a parked car for hour after mind-numbing hour. Jones says he never gets bored.

“I love surveillance. I could be sitting there for six hours and nothing happens. But that seventh hour …”