A Will County K9 unit discovered more than five kilograms of heroin and methamphetamine hidden in a vehicle during a traffic stop late Saturday near southwest suburban Joliet.

Javier Gomez-Mendoza | Will County sheriff's office photo

Javier Gomez-Mendoza | Will County sheriff’s office photo

About 11:20 p.m., Deputy Brett Bartunek and his K9 partner Sem were eastbound on I-80 near Larkin Avenue in Joliet when Bartunek noticed a 2007 Dodge Caliber with no registration lights making illegal lane changes, according to the Will County sheriff’s office.

Bartunek pulled the vehicle over and spoke to the driver, 58-year-old Javier Gomez-Mendoza of North Glen, Colorado, according to the sheriff’s office. He said he was traveling to visit his daughter in Boston.

A second deputy arrived at the scene and while he checked Gomez-Mendoza’s Mexican driver’s license, Bartunek had Sem perform a sniff test on the vehicle.

Sem alerted to a probable presence of narcotics in the rear side of the vehicle, according to the sheriff’s office. Gomez-Mendoza gave the deputies permission to search the vehicle, and Bartunek noticed several suspicious markings on the muffler.

Gomez-Mendoza and the Dodge Caliber were taken to the sheriff’s office, and the vehicle was placed on a lift. Sem accessed the bottom of the undercarriage and again alerted to probable narcotics in the muffler area.

The muffler was inspected further and it appeared to have mud on it, but there was no mud on the rest of the vehicle, according to the sheriff’s office.

Three bricks of heroin, weighing 3.4 kilograms, and six packages of methamphetamine, weighing more than 2.8 kilograms, were found hidden in the muffler, according to the sheriff’s office. The packaging had been covered in black pepper in an unsuccessful attempt to hide the odor.

Gomez-Mendoza was charged with possession of a controlled substance with intent to deliver, according to the sheriff’s office. He is being held at the Will County Adult Detention Facility.