An autopsy report has confirmed that a Mexican high school student died from drinking highly concentrated liquid methamphetamine as he tried to persuade customs inspectors at the San Diego border it was apple juice.

Cruz Marcelino Velazquez, 16, volunteered to take a “big sip” of the liquid at an entry port Nov. 18, according to an autopsy report released Wednesday. After drinking the liquid meth, he was handcuffed and taken to the security office. He began screaming in pain and yelling “the chemicals” and “my heart!” the Associated Press reports. He died hours later at a hospital from acute methamphetamine intoxication.

The San Diego County Medical Examiners report does not say whether officials asked him to drink the liquid, or whether they tried to stop him after he volunteered to do so. U.S. Customs and Border Protection had no comment on the incident, according to the Associated Press.

San Ysidro, the busiest border crossing in the U.S., has become a major passageway for meth smuggling as Mexico’s Sinaloa cartel has grown in the area. Smugglers dissolve the crystal methamphetamine in water and hide it in juice bottles, windshield wiper fluid containers and gas tanks as they cross the border. Later it is converted back into crystals to sell in the U.S.

Children are caught with meth several times a week at the border crossing, according to Joe Garcia, assistant special agent in charge of U.S. Immigration and Customs enforcement investigations in San Diego. They are paid between $50 and $200 for each trip.

[AP]