Police in New Mexico are investigating the robbery of a $1.5 million diamond inventory after a North Carolina broker made a brief stop and left the jewels inside a rental car.

Within three minutes, a case carrying more than 150 stones and 70 rings was gone.

Investigators say broker Peter Kaplan of New Port, N.C., had just arrived in town Wednesday. He picked up a rental car and a hotel room and was en route to a jewelry store when he decided to stop for a restroom break.

Police believe the thief might have been following him.

The cheapest diamond in the case was worth $2,500. One was worth more than $100,000.