CHICAGO (AP) — The way the FBI tells it, William Rosario Lopez put on a surgical mask and walked into the Connecticut convenience store looking to the world like a typical pandemic-era shopper as he picked up plastic wrap, fruit snacks and a few other items. Then, when the only other customer left, he went to the counter, pulled out a small pistol, pointed it at the clerk and demanded that he open the cash register.

The scene, the FBI contends in a court document, was repeated by Lopez in four other gas station stores over eight days before his April 9 arrest. It underscores a troubling new reality for law enforcement: Masks that have made criminals stand apart long before bandanna-wearing robbers knocked over stagecoaches in the Old West and ski-masked bandits held up banks now allow them to blend in like concerned accountants, nurses and store clerks trying to avoid a deadly virus.

“Criminals, they’re smart and this is a perfect opportunity for them to conceal themselves and blend right in,” said Richard Bell, police chief in the tiny Pennsylvania community of Frackville. He said he knows of seven recent armed robberies in the region where every suspect wore a mask.

Across the United States, masks have become more and more prevalent, first as a voluntary precaution and then as a requirement imposed by governmental agencies and businesses. And people with masks — as well as latex gloves — have found their way into more and more crime reports.

Just how many criminals are taking advantage of the pandemic to commit crimes is impossible to estimate, but law enforcement officials have no doubt the numbers are climbing. Reports are starting to pop up across the United States and in other parts of the world of crimes pulled off in no small part because so many of us are now wearing masks.