The Didier family of Rocklin, California, just outside Sacramento, likes Christmas movies. The day after Christmas last year, Chris Didier and two of his three children sat down to watch "National Lampoon's Christmas Vacation" one more time.
When the movie ended, Zach, 17, a track star, straight-A student and self-taught musician with his sights set on Stanford, headed to his bedroom.
As Chris recalls, his son said: "I had a good time. Love you, Dad. Good night."
At noon the next day, when Zach didn't answer a knock on his door, Chris entered his bedroom. Zach was slumped over the computer keyboard at his desk, where he had filled out his college applications just weeks before.
"You never imagine there would be danger," Chris said, his voice cracking. "You would think your child's safe when they're at home. You would think they would be safe when they're in their room."
Chris and Zach's mother, Laura, say their son — who would have turned 18 this week — bought what he thought was a prescription pain pill from someone he met on Snapchat. They don't know why Zach bought it — perhaps for soreness from his workouts, perhaps to help him sleep.
The pill was counterfeit, and it contained a lethal amount of the powerful opioid fentanyl.
The Drug Enforcement Administration made a huge bust this month in Mexico, seizing 600,000 counterfeit pharmaceutical pills. They're made to look like real prescription drugs of various types, and they would have been sold as anything from Adderall to Percocet to Xanax, but they actually included fentanyl, which is up to 50 times more powerful than heroin. The DEA worries that traffickers who are trying to fool casual drug users into buying "prescription" drugs are going to wind up killing them.
Ray Donovan, the DEA's special agent in charge in New York, showed NBC News a batch of phony oxycodone pills that look exactly like the real things.
Traffickers use fentanyl, Donovan said, because "it's cheap, it's synthetic, it's easy to make and it's so lucrative."
Just 2 milligrams of fentanyl can kill an adult, according to the DEA, and there is no quality control. Donovan estimated that 1 in 4 of the pills seized by the DEA has enough fentanyl to pose the risk of death.
Some of the pills are pressed in pill machines in the U.S., but most are made in Mexico. Donovan said it's an attempt by traffickers to expand their market.
"When we first saw fentanyl come into the U.S., we saw the hard-core street users utilizing heroin mixed with fentanyl," he said. "With the pills, they're trying to draw in young adults, high schoolers — you know, people on the weekend that never used drugs or don't have an addiction problem."
Donovan said the chance that any so-called prescription drug purchased via social media might contain fentanyl is "very high." Fentanyl-related deaths in the U.S. hit 36,000 in 2019, the most recent year for which figures from the Centers for Disease Control and Prevention are available, but it isn't known what proportion is related to counterfeit pills. The CDC says preliminary numbers indicate that deaths from synthetic opioids have accelerated during the Covid-19 pandemic.
In January, federal authorities in Sacramento issued a multi-count indictment accusing 10 people from California and Nevada of trafficking in fentanyl-laced oxycodone pills. Prosecutors said wiretaps showed that the defendants were aware that multiple deaths in the Sacramento area had been linked to the pills.
Chris and Laura Didier recently attended the arraignment of a man charged with selling Zach the counterfeit pill that led to his death. The man hasn't yet entered a plea.
They want those responsible to be held accountable, but they also want to warn the public.
"As soon as we started putting the puzzle together, it was, like, we need to ring the alarm bells," Laura said, "because we don't want anyone else to go through this. We don't want anybody else to go through this."