The delivery driver kept calling back to report another burglary and each time he did David Larsen understood the suspect was likely someone he knew.

Larsen and his brother are owners of The Donut Professor. "We started with two locations and now we're at seven, thinking about eight," said Larsen.

Four of those locations were burglarized in a two-hour span earlier this week. "There was no sign of forced entry, someone used a key at each store," recalled Larsen.

A small amount of cash was taken from each location, but so far police have not made any arrests. "We're dealing with different agencies because the stores were in Bellevue, La Vista, Elkhorn and Omaha."

Click the video to see what other evidence was left behind.