Fake oxycodone pills containing fentanyl are increasingly popping up on Twin Cities streets, alarming health officials and prompting law enforcement agencies to quickly switch gears to stem their flow into the region.

In recent months, the counterfeit "MBox" pills, named for their signature imprint, have been blamed on "a large number of overdoses and overdose deaths in numerous cities throughout Minnesota," a Minneapolis gang investigator wrote in a search warrant affidavit filed earlier this month. Local authorities have seized thousands of the pills, which are designed to look like brand-name 30mg oxycodones, but are laced with unpredictable amounts of fentanyl and its analogues, compounds that share structural similarities.

Yet the product keeps pouring into the region and into the hands of small-time dealers and gang members who peddle it for $35 a pill.

"It makes a deadly substance, fentanyl, really accessible and really cheap and it makes it even more deadly if it's disguised as something that we know," said Julie Bauch, Hennepin County's opioid response coordinator. "But, do they know if it's a fentanyl synthetic or another synthetic or in what dose? They don't know."

A spike in overdoses linked to fentanyl has sent health officials and policymakers rushing to find long-range solutions, just as the opioid epidemic appeared to be slowing in parts of the country. According to preliminary data from the Hennepin County Medical Examiner's Office, deaths related to fentanyl continued to rise in the county last year, mirroring a national trend, though it's difficult to say how many of those fatalities were caused by pills.

At least 135 people died from fentanyl or fentanyl analog overdoses countywide in 2019 — a tenfold increase from the number that fatally overdosed in 2015, the last year for which reliable data are available. Overall, opioid-related deaths ticked up slightly, to 170 last year from 163 in 2018, but were still down from the five-year high of 197 recorded in 2017.

Experts say the white powder, which is 50 times stronger than heroin and can be lethal to non-opioid users in even small doses, is being cut into other opioids to produce a longer-lasting and more potent high.

Its rise in popularity has been driven in part by other trends, like "speedballing" — where addicts mix depressants like heroin to counter the stimulating effects of cocaine — which has seen a recent resurgence, according to Bauch.

Federal agencies like the Drug Enforcement Administration, Bureau of Tobacco, Firearms and Explosives and FBI have partnered with local police departments and regional drug task forces to go after local dealers suspected of trafficking the illicit pills.

In one such case, Demarlo Hudson, 33, was indicted by a federal grand jury on drug trafficking charges, after being busted selling large numbers of fentanyl-laced oxycodone pills across the metro area. His case was part of a monthslong investigation — involving controlled buys, informants and surveillance — of a large-scale prescription pill and marijuana operation, which was partly run out of Hudson's music studio in New Hope, authorities say.

Stephanie Devich, a harm reduction specialist with Valhalla Place, which does addiction outreach across the Twin Cities, said that fentanyl pills have been around for years now, but have grown in popularity recently as users are looking for new, cheaper ways to deal with their addictions.

"Anybody can make a pill — you can buy a pill press online," Devich said. And it's not just oxycodone, either, she added, saying that she had heard anecdotally that people were overdosing on fake Percocet and Xanax pills in New Brighton, St. Paul and Mankato, where they're being sold for as little as $10.

"Sometimes it's like three for $10 if you're a good customer," she said. "Fake Oxys" are also emerging as far away as Northfield, she said, sometimes laced with carfentanil, an even more potent cousin of fentanyl.

Friends of Alexis Alijai Lynch, a promising young rapper who went by Lexii Alijai, told officials that she overdosed on New Year's in a downtown Minneapolis hotel room after taking Percocet; an autopsy later determined that she died of an accidental overdose from a combination of fentanyl and alcohol. An investigation into the 2016 overdose death of musician Prince revealed that pills marked as hydrocodone that were seized from Paisley Park actually contained fentanyl.

Fentanyl can be prescribed legally, often coming in the form of a patch, and has for years been used as an anesthetic in surgery and for severe pain relief. Because of its potency, many versions of the drug are already outlawed in the U.S., but authorities say that regulation is difficult because manufacturers are constantly tweaking the recipes of their drugs to skirt existing laws.

In 2016, the DEA issued an intelligence brief warning about the increasing number of small-time manufacturers buying pill presses and fentanyl cheaply online and then making their own fake pills to sell on the black market, for large profits. Dealers stood to reap huge profits by no longer depending on drug cartels for a steady supply of product.

The problem is that most manufacturers aren't mixing the fentanyl correctly, sometimes leaving users and even dealers themselves guessing at the potency of the drugs they're buying, said Brian Marquart, statewide gang and drug coordinator for the Minnesota Department of Public Safety Office of Justice Programs.

"The Oxy-30 look-alike tablets have been around for a while, but there has been a resurgence of them lately," he said. "They don't have to go out on the street and source them, so to some people they feel that it's more legit."

A report released earlier this year by the Centers for Disease Control and Prevention showed that drug fatalities in the U.S. declined in 2018 for the first time in nearly three decades, although overdose deaths tied to synthetic opioids like fentanyl continued to rise.

Locally, their prevalence has exploded, authorities say.

Last November, DEA agents at Minneapolis-St. Paul International Airport intercepted a FedEx package containing nearly 2 pounds of MBox pills, which was addressed to a house in Savage, authorities say.

A month later, a 25-year-old man was found by his brother after overdosing in an apartment in Bloomington. Police recovered a small clear plastic baggie with nine blue pills, with "M" imprinted on one side and "30" on the other, from another room. An autopsy later concluded that he died of a fentanyl overdose, according to court filings.

And a few weeks ago, two people overdosed on fentanyl pills within hours of each other in St. Louis Park. A preliminary police investigation indicated that they had likely purchased the drugs from the same dealer.