Police spokesman John Mirabelli said Friday the men were spotted on security video climbing stairs inside North America's second-tallest building in downtown Chicago.
The trio of BASE jumpers - one wearing a dress shirt and tie - "breached" a lock early Thursday. They managed to make it to the roof, strap on parachutes and float to the ground. The daredevils got away.
Authorities want to speak with witnesses who either saw the men jump from the 1,389-foot-tall building or watched them land. Investigators are also culling through video.
The three could face trespassing and other charges.