A man is under arrest after Border Patrol agents at the Falfurrias checkpoint found approximately 125 pounds of cocaine valued at nearly $4 million hidden within his vehicle.

Authorities arrested Jose Guillermo Silva-Martinez on Friday after he tried to smuggle the drugs through the checkpoint with his son, who is not currently facing charges and told Border Patrol agents he had no knowledge of the cocaine hidden within the vehicle, according to a criminal complaint.

Silva arrived at the checkpoint that day at approximately 1:35 p.m. in a gray 2010 Ram 2500 with Nuevo Leon, Mexico license plates.

At the checkpoint, Silva told a Border Patrol agent that he was headed to Robstown with his adult son and both men provided border crossing visas and 1-94 cards.

The agent noticed that both Silva and his son were “stiff and robotic like” while reviewing the visas and asked whether anyone was in the vehicle and if Silva could lower the rear driver’s side window.

“Silva-Martinez simply stated ‘No’ and lowered the rear window,” the complaint stated.

The agent noticed they had no bags or cargo in the vehicle so he asked what they were going to do in Robstown and how long they planned to stay.

Silva did not elaborate and said they were returning home the same day, which the agent found odd, according to the complaint.

The agent then referred Silva to secondary where an X-ray examination was conducted on his vehicle, which is where agents found an anomaly in the bed of the truck.

“An inspection of the bed revealed an aftermarket hidden compartment built under the bed of the truck containing what appeared to be multiple black bundles,” the complaint stated. “Once the aftermarket compartment was opened, Agents observed approximately fifty … bundles of suspected narcotics wrapped in black carbon paper and clear cellophane wrap within the compartment.”

The bundles weighed just under 125 pounds and had an estimated street value of $3,998,615.29, according to the complaint.

A records check revealed that Silva crossed the Falcon Dam port of entry at approximately 10:01 a.m. where he told U.S. Customs and Border Protection officers that he and his son were traveling from Monterrey to McAllen to shop for purses to resell in Mexico, according to the complaint.

“They would travel to Pearland if they could not find merchandise in McAllen,” the complaint stated. “Silva-Martinez also stated he and his son are lawyers in Mexico and his son just graduated.”

Border Patrol agents at the Falfurrias checkpoint determined the men had not gone shopping.

Silva requested an attorney but his son, who is not identified in the complaint, spoke with investigators.

The son told agents that his father called him on Feb. 27 and asked if he would go with him to San Antonio to pick up his aunt.

He also told agents that CBP stopped them at the Falcon Dam port of entry for approximately an hour before they traveled to the Falfurrias checkpoint where they were again stopped.

“Son stated that after they picked up their aunt, they were going to drive to Houston and stay the night,” the complaint stated.

He then said that they would return to McAllen and shop for clothing.

“Son stated he did not know about the drugs that were in the truck and stated the truck belongs to Silva-Martinez,” the complaint stated.

Silva was scheduled to make a first appearance Monday morning in Corpus Christi federal court in front of U.S. Magistrate Judge Mitchel Neurock.