$120,000 was seized from a truck driver during a traffic stop last week, launching a federal investigation into the origins of the cash.

The semi truck was stopped on Thursday, November 9th after failing to use its blinker while traveling on Highway 59 through East Montgomery County, Texas.

“A deputy constable pulled over the truck when the driver didn’t use his traffic signal and made some other violations,” said police spokesperson Sgt. James Slack.

The truck driver, who has only been identified as a Mexican National, only spoke Spanish, so deputies had to go through a translator. Through the translator, officers were told that the truck driver was on his way to Livingston, Texas to pick up a load of fertilizer and take it back to the Texas Valley, reported The Houston Chronicle.

“He had nothing in the back of the truck. Trucks don’t usually go anywhere empty. His story had some holes in it… There was also a strap hanging down from the back wheel that we later found out was helping to hold up the suspension,” Slack continued.

A K-9 officer was then brought on scene where he inspected the length of the tractor trailer, alerting officers to several “positive hits,” giving officers probable cause to search the truck.

During the search of the truck, no narcotics were found, but officers did discover $120,000 worth of $20 bills in a hidden compartment inside the big rig. Investigators believe that the dog alerted officers to the presence of narcotics because the trailer and cash had recently been in contact with the drugs.

The officers then seized the bundles of cash and turned the investigation over to the federal authorities.

“The federal authorities are now in charge. They chose to release the driver and the truck, and further investigate the case,” Slack added.

No charges against the truck driver have been filed as authorities continue to look into the case.