PORTLAND, Maine — Federal officials say the recent discovery of $1.5 million in cash in the back of a tractor trailer on the Maine Turnpike is more evidence that bulk cash smuggling is on the rise.

A U.S. Immigration and Customs Enforcement (ICE) official told Foster’s Daily Democrat in Dover, N.H., that bulk cash smuggling is on the rise as drug dealers, human traffickers and other criminals try to move proceeds in a manner that avoids getting financial institutions involved.

Maine State Police on Sept. 3 seized what is now estimated to be more than $1.5 million in U.S. currency found in buckets in a Texas-registered tractor trailer that was pulled over for a routine inspection near the York tolls.

Maine State Police Lt. Thomas Kelly has said the incident was the largest seizure of its kind in the state’s history, with the money being held at a secure facility pending an investigation that will include a formal count of the cash.

Police say the truck was headed south on Interstate 95 when it was pulled over and brought to a weigh station in Kittery, where a trooper opened the back to find stacks of money bundled inside buckets lined with trash bags.

Kelly said police found that the driver, John Rivera-Ramirez, 35, had false trucking logs. Jose Javier Perez, 46, was a passenger in the vehicle, according to authorities.

Both men are said to have possessed Texas driver’s licenses.

Rivera-Ramirez was arrested and charged with having false truck logs and since has been released on bail. Perez has not been charged.

Maine authorities are saying little about the investigation, but have called in ICE to assist.

An ICE official said the Maine case represents a sizable sum and the federal agency will help troopers follow the money trail to determine where the cash came from, how it was earned and where it was being brought.

Maine authorities have yet to bring cash smuggling charges against the driver or passenger.