The state and federal authorities are offering a $50,000 reward for information leading to the arrest of a man who abducted a 7-year-old boy who was found a day later about 100 miles from home.

The Florida Department of Law Enforcement and FBI offered the reward Thursday, three days after Bryan Williamson knocked on a door in Jacksonville seeking help. He had been abducted Sunday evening while playing outside a home in Madison, more than 100 miles west of Jacksonville.

The woman who opened her door Monday morning and saw the upset boy thought he might be the subject of an Amber Alert she had seen. She called police, who reunited him with his parents.

Investigators Thursday also released surveillance video they believe shows the car used in the abduction.