Poor Roman Polanski. The fugitive film director thought he was going to Zurich to pick up a lifetime achievement award and ended up in a detention cell, fighting over whether he should be returned to Los Angeles on a 1977 conviction for having sex with a child.

Of all the dirty tricks.

Never mind that Polanski pleaded guilty to the crime, which involved champagne, half a Quaalude, a hot tub and a 13-year-old girl.

He spent 42 days in a state prison undergoing psychiatric evaluation, believing he’d cut a deal with prosecutors to avoid further time. But then he got word that the judge might not go along with it. So instead of going to prison, he went to France.

It was a natural choice. France has no extradition treaty with the United States and apparently no problem with middle-age guys preying on barely teenage girls. For three decades, Polanski made films, raised a family and traveled all over Europe, celebrated by his new countrymen and unmolested by his old ones. French authorities were aghast when American prosecutors finally came after him.

France’s foreign minister described the arrest as “a little sinister.” Its minister of culture said the director was “thrown to the lions for an old story.” Hollywood stars complained that this case is three decades old. Other defenders of Polanski described his arrest as shocking, vindictive, disgraceful.

Nobody in Hollywood used the word that comes first to our mind: overdue. This is a three-decade-old case because he fled.Why didn’t Los Angeles County prosecutors pick him up sooner? Their story is that they’ve been trying all along. They succeeded, finally, because they had plenty of notice that he’d be in a place where he could easily be cuffed.

The fact that it took 31 years suggests some measure of ineptitude or indifference. A 2008 documentary suggests worse: “Roman Polanski: Wanted and Desired,” released at last year’s Sundance Film Festival, alleges misconduct on the part of prosecutors and the judge, who is now dead. Basing their case partly on the film, Polanski’s lawyers asked a judge in December to throw out the case.Imagine the embarrassment for prosecutors, trying to fight that appeal while Polanski flits all over Europe, hiding in plain sight as he has for three decades. Is that why they finally popped him? It doesn’t matter.

Polanski’s apologists seem to think he deserves a pass because (pick one) he’s 76, he had a tragic childhood, the crime happened long ago, he’s a genius, his victim has publicly forgiven him, he’s made some memorable movies _ and, by the way, there’s another one in the works, only now it’s on hold.

None of that changes the fact that he pleaded guilty to having sex with a 13-year-old and never faced the music. Let him come back to Los Angeles and explain to a judge, and to all of us, why that’s OK.