It began with the death of a 20-year-old mom just a month after her baby boy's first birthday.

A estrange boyfriend FaceTime me. He told me she was not moving.

Another American lost to the scourge of fentanyl. And what did the police tell you about what they learned shortly afterwards?

Well, the police just told me that it was an overdose.

Law enforcement couldn't save Diamond Lynch, but they could seek justice for her.

We have something we call OD justice.

Anne Milgram is the DEA administrator.

We're getting photos every day.

Her agency partners is honored with local law enforcement. Their goal?

To stop the traffickers and the source of supply, stop every single part of that supply chain that killed Diamond Lynch and also is killing other Americans.

They started with her.

Cell phone. Everybody has a cell phone in their pocket, and that basically means everyone has a drug dealer in their pocket.

Much of the dealing done out in the open.

The fentanyl that's killing Americans are being sold on Snapchat, on TikTok, Facebook, marketplace, Instagram, openly, and on the open media.

From text and Instagram messages, they found the people who sold Diamond the pills. One of them seen here, brazenly, flashing handfuls of money. They've since been convicted and sentenced to lengthy prison terms. From there, investigators went higher. We expanded our investigation and identified each rung of the spentinal supply network. Tracing their cell phones and Instagram messages to find the people who supplied the dealers with the deadly drug. That network included wholesalers in California, selling product made in Mexico with chemicals imported from China, even bragging about the quality of their product on Instagram. Often, authorities say they smuggled pills in candy boxes like these. So far, 25 people have been charged. All but two have pleaded not guilty.

We've been able to trace more than a million potential deadly doses of fentanyl coming to the Washington, D. C. Area in one year.

That's her prom picture.

Right there. Diamond's mother, now raising her grandson, wants everyone to understand the lethal risk of fentanyl.

Definitely, one pill can kill. It's chemical warfare on American citizens, period.

A tragic death brings a measure of justice. Kent Delaunian, BBC News, Washington.

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