Last May, congressional staffers started with a very simple question: In the midst of the worst drug crisis in American history, exactly how easy is it for the average person to order some of the deadliest drugs on the planet over the internet and have them delivered to their home from the other side of the globe?

The answer, they revealed this week, is: shockingly easy.

At a briefing on Wednesday, several Senate investigators working for Sens. Rob Portman (R-OH) and Tom Carper (D-DE) detailed to reporters exactly how simple it is to order fentanyl, a synthetic opioid that has overtaken heroin and prescription painkillers to become the biggest killer of Americans, online. They have been working on this investigation since last year, and their full findings will be reviewed at a Senate hearing on Thursday.

“We must keep this poison off our streets and out of our communities,” Portman said in a statement accompanying the staff’s report. “We now know the depth to which drug traffickers exploit our mail system to ship fentanyl and other synthetic drugs into the United States.”

There isn’t any silver bullet to the drug crisis. A lot of experts would say that tackling demand and making treatment more accessible should be the top priority. Still, this new Senate report reveals in stunning detail just how easy it is to order some of the most potent opioids available from the other side of the world.

It is shockingly easy to order fentanyl and synthetic opioids online

The staff started, quite literally, by Googling “fentanyl for sale,” they said. They found pages and pages of advertisements. Posing as first-time buyers, they made contact with six responsive sellers. These sounded like sophisticated operations, offering discounts on bulk purchases and even trying to upsell the investigators to carfentanil, an even more powerful opioid.

The sellers preferred Bitcoin, the investigators said, but they also accepted Western Union transfers, PayPal, and prepaid credit cards. They wanted to ship the packages through the international arm of the US Postal Service, rather than a private carrier like FedEx or UPS. They told the investigators that there was less of a chance the package would end up detained — we’ll get back to that in a moment.

It was that easy. The investigators didn’t actually execute a purchase, because even a small amount of fentanyl can be lethal. But they learned how simple it was to buy these powerful opioids online and how brash the sellers were.

At one point, when China cracked down on a specific strand of fentanyl, the sellers advertised “a hot sale” — the top of the email, which the staff included in their report, literally said: “JUNE SPECIAL OFFER” — to try to empty their reserves before the ban went into effect.

Using payment and shipment information that the sellers themselves provided, the Senate investigators identified 500 transactions in 43 states adding up to $766 million worth of fentanyl, going by its street value, just from these six sellers. They found people who were purchasing for personal use — including seven who overdosed and died — as well as the people buying to set up their own distribution network in America.

It became clear how adaptable the fentanyl sellers were. Now that shipments from China have come under suspicion, the sellers told the investigators that they preferred to ship through Europe. Even as the US worked with China to crack down on one fentanyl compound, the sellers simply tweaked their formula and offered to sell a new version in another email included in the report.

”They just made a derivative,” one investigator told us. “You schedule one, they change the chemical compound a tiny bit, another one pops up.”

Lawmakers want to crack down on illicit opioid shipments

The underlying message of the report was that the US Postal Service should do more to crack down on these illicit shipments. Right now, private carriers are required to collect advanced electronic data, a bar code with information about the sender, the recipient, and what is in the package. But the Postal Service and its foreign counterparts do not. That’s precisely why sellers prefer the US Postal Service over FedEx or UPS.

Having that electronic data, the Senate staff said, would make it easier for customs agents to identify suspicious packages before they ever reach the United States and divert them once they arrive.

Portman and a bipartisan group of senators have actually introduced legislation to require the Postal Service to collect this electronic data. It is also an idea that President Trump has at times endorsed. There are hurdles, including international treaties and the readiness or willingness of other countries to implement the same standards. But absent the passage of a bill — this plan has been introduced in previous Congresses too — lawmakers are pushing the Trump administration, particularly the State Department, to do more to bolster international shipping standards.

Such a law could only help so much. Even through the narrow lens of cutting the drug supply, the sellers have already proven adept at adapting to new circumstances. Still, the investigators made the case for more action.

”It’s another step to make it as difficult as possible to get drugs into the country,” an investigator said. “Make it more expensive, make it harder to get them. Every little bit helps.”

Opioids have become a major problem in the US, even if Congress hasn’t given it that much attention

Fentanyl and other synthetic opioids have now surpassed heroin and prescription painkillers as the deadliest drugs in the United States. They killed more than 19,000 Americans in 2016, topping heroin (15,000) and prescription opioids (14,000) for the first time.

As Vox’s German Lopez previously explained, fentanyl has been around since the 1960s, but its illicit use has spiked in recent years. It is relatively easy to produce and is much more potent than heroin. Law enforcement officials believe that China is the primary source of illicit fentanyl, where it can be produced in labs without government oversight and shipped to the United States through the Postal Service.

But as Lopez has detailed time and again, cracking down on supply — as the Portman bill would — doesn’t do anything to address demand or treatment, which many experts name as the bigger issues.

Congress passed its first major opioids legislation and funding in late 2016 but hasn’t done much since to follow up. And so far, the Trump administration’s response to the opioid crisis — a regular talking point for the president on the campaign trail — has been severely lacking in those other, arguably more pressing areas.

So there is a whole lot more to do than this. Nevertheless, I found the briefing a sobering reminder of the challenges federal officials face — and the ever-changing nature of the crisis.