Daniel Mensah of Worcester, Mass., was involved in a minor accident at the Great Egg Toll Plaza in 2012. Authorities say his wallet fell from his lap to the ground when he got out of his vehicle.
State troopers reviewed surveillance video and saw Giberson remove the wallet, which contained $400 in cash.
Giberson faces up to 180 days in jail and up to $10,000 in fines when he's sentenced in December.
Giberson has worked for the turnpike for 16 years.