off tonight. >> reporter: it's 6:21 on a monday evening at the san ysidro, california border crossing. and the man in the white sweatshirt is a smuggler. a 16-year-old high school student by the name of cruz velasquez, with drugs hid nen two bottles in his shoulder bag. >> cruz was believe, as a mule. here, we'll give you $100 or $200 if you just take these bottles across the border. >> reporter: over the next one hour and 38 minutes this video obtained by abc news will show in gripping detail just how far u.s. border officers will go, encouraging or at least permitting this teenager to prove his innocence by drinking from a suspicious bottle, an encounter that will end up as a matter of life and death on the border. >> there is a clear history of agents and officers engaging in what i believe was serious misconduct. >> reporter: and our abc news investigation conducted with the non-profit investigative fund found that despite more than ten suspect deaths and hundreds of other allegations of misconduct and threats border officers and agents are rarely prosecuted or even punis

san ysidro, california, just south of san diego. more than 75,000 people a day coming into the country at the busiest border crossing in america. among them, smugglers. it's 6:21, on a monday evening, and the man, in the white sweatshirt, is a smuggler. and tonight, he will be caught on tape trying to smuggle drugs into the country, methamphetamine, hidden in two plastic bottles in his shoulder bag. >> they are bringing drugs. >> reporter: the kind of activity that will later lead candidate donald trump to call for tougher border security. >> we have some bad hombres here and we're going to get them out. >> reporter: the target on this night is a high school student, 16-year-old cruz velazquez of tijuana, believed to be making his very first run as a smuggler. over the next 1 hour and 38 minutes, this video, now obtained by "20/20" 3 1/2 years after it happened, will show for the first time, in gripping detail, just how far u.s. border officers will go in an encounter that will end up as a matter of life and death on the border. >> 16-year-old children will do things that are v