At first, an epidemic of absent-mindedness seemed to have broken out.

One purse was found just sitting on a display shelf in the shoe department at Macy’s. Another one turned up downstairs, in Macy’s Cellar. Yet another rested on a chair in a Midtown McDonald’s, left by a woman who had stepped into the restroom.

In fact, all three items had been planted by police officers in plainclothes during the previous six weeks. And the three people who picked them up were arrested, and now face indictment on charges that could land them in state prison.

Nine months ago, a similar police decoy program called Operation Lucky Bag was effectively shut down by prosecutors and judges who were concerned that it was sweeping up the civic-minded alongside those bent on larceny. Shopping bags, backpacks and purses were left around the subway system, then stealthily watched by undercover officers. They arrested anyone who took the items and walked past a police officer in uniform without reporting the discovery.

Now, a new version of the operation has started to catch people in public places outside the subways, and at much higher stakes, Criminal Court records show.