I assume I don’t have to explain last week’s Louvre jewel heist. I love a good caper, and have (like many others) eagerly followed the details. An electric ladder to a second-floor window, an angle grinder to get into the room and the display cases, security guards there more to protect patrons than valuables—seven minutes, in and out.

There were security lapses:

The Louvre, it turns out—at least certain nooks of the ancient former palace—is something like an anopticon: a place where no one is observed. The world now knows what the four thieves (two burglars and two accomplices) realized as recently as last week: The museum’s Apollo Gallery, which housed the stolen items, was monitored by a single outdoor camera angled away from its only exterior point of entry, a balcony. In other words, a free-roaming Roomba could have provided the world’s most famous museum with more information about the interior of this space. There is no surveillance footage of the break-in.

Professional jewelry thieves were not impressed with the four. Here’s Larry Lawton:

“I robbed 25, 30 jewelry stores—20 million, 18 million, something like that,” Mr. Lawton said. “Did you know that I never dropped a ring or an earring, no less, a crown worth 20 million?”

He thinks that they had a compatriot on the inside.

Museums, especially smaller ones, are good targets for theft because they rarely secure what they hold to its true value. They can’t; it would be prohibitively expensive. This makes them an attractive target.

We might find out soon. It looks like some people have been arrested

Not being out of the country—out of the EU—by now was sloppy. Leaving DNA evidence was sloppy. I can hope the criminals were sloppy enough not to have disassembled the jewelry by now, but I doubt it. They were probably taken apart within hours of the theft.

The whole thing is sad, really. Unlike stolen paintings, those jewels have no value in their original form. They need to be taken apart and sold in pieces. But then their value drops considerably—so the end result is that most of the worth of those items disappears. It would have been much better to pay the thieves not to rob the Louvre.