PINE VALLEY, Calif. -- Within the last two days U.S. Border Patrol agents seized 36 pounds of crystal methamphetamine and 91 pounds of marijuana concealed inside the rooftops of two separate vehicles, said Jerome Conlin, a Border Patrol spokesman.

Border Patrol agents found a 36-pound stash of methamphetamine hidden in a sport utility vehicle that entered a checkpoint in the East County highlands Friday.

The Nissan Xterra pulled into the inspection station on Interstate 8 in Pine Valley about 8:30 a.m., according to Customs and Border Protection officials.

While officers looked over the SUV, a service dog alerted them to an after-market compartment welded to the roof of the vehicle. Inside the chamber were two dozen bundles of methamphetamine with a combined estimated street value of nearly $550,000.

The man driving the Xterra, a 21-year-old Mexican national, was arrested.

The second seizure occurred Thursday at 11 a.m., when a Ford Taurus driven by a 39-year-old male U.S. citizen approached the Interstate 8 checkpoint.

During the checkpoint inspection, the driver appeared nervous and gave agents several misleading statements. Agents also noticed an irregularity in the rooftop of the vehicle, Conlin said.

Agents conducted a further search and found 23 bundles of marijuana concealed inside the rooftop. The marijuana had a total weight of 91.1 pounds and an estimated street value of $54,660.

Both suspects and the drugs were turned over to a multi-agency, anti-drug task force, Conlin said.