A yearlong investigation by local and federal law enforcement agencies has led to multiple charges in what authorities said was the first drug trafficking operation to focus on fentanyl distribution in the Twin Ports.

While police have reported a surge in the use of heroin and other prescription and street drugs over the past five years, fentanyl is a synthetic opioid that is said to be up to 50 times more potent than heroin.

"We've done these roundups before but the significance of this is it's first time we've had a large drug trafficking organization in this area selling fentanyl," said Duluth police Lt. Jeff Kazel, commander of the Lake Superior Drug and Violent Crime Task Force. "It's the new era that we're running into."

Authorities announced Monday that they had charged seven people with felony offenses in connection with the alleged conspiracy. The investigation involved the execution of search warrants in Duluth and St. Paul and led to the seizure of fentanyl, heroin, methamphetamine and hundreds of prescription pills, along with nine firearms and more than $21,000 in cash.

The ring was allegedly operated from inside a Wisconsin prison by 36-year-old Aaron Andre Reynolds and from outside by 31-year-old Joshua John Wilding, using a network of drug dealers and gun traffickers.

Kazel described fentanyl as "the trend throughout the United States" in the illegal drug distribution industry.

"Fentanyl at one point will overtake heroin," he said, "because it's easier for them to get and manufacture, it's cheaper for them (and) it takes a smaller quantity for them to get to a dosage unit for somebody that wants to sell it so they can make more money."

Reynolds was incarcerated in the Douglas County Jail, and later a state prison, on unrelated drug charges while investigators monitored regular phone calls he placed to Wilding, according to a criminal complaint.

"It was clear from the jail phone calls that defendant Reynolds actively and regularly directed defendant Wilding in the art and science of the illegal drug trade," the document states.

"Investigators recorded numerous calls wherein defendant Wilding took orders from defendant Reynolds as to how to sell controlled substance, introduced defendant Wilding to sources of the controlled substances and shared in the proceeds of the illegal drug trade that defendant Wilding maintained during this time period."

Kazel said the fentanyl would sell for $100-$200 a gram, while prescription pills would sell for approximately $80 apiece. The operation was estimated to bring in about $100,000 a month.

The investigation was the result of a cooperative effort between the Duluth and Superior police departments with assistance from two federal agencies - the Drug Enforcement Administration and the Bureau of Alcohol, Tobacco, Firearms and Explosives.

Duluth Police Chief Mike Tusken said the strength of the local task force and the willingness of agencies to share intelligence are keys to fighting drug-dealing networks.

"This may be one of the worst places in the country to come and be involved in the drug trade because we are just a big enough community that we have great resources but also we share data very well and have great relationships with our partner agencies," he said.

Duluth in recent years has had one of the highest per capita rates of drug overdoses in the state. The city has seen five fatalities this year - a number that authorities believe would be much higher if not for the widespread availability of naloxone, an overdose reversal drug.

The Duluth Police Department and other agencies covered by the task force area all carry naloxone, and Tusken said efforts are being made to distribute it to other areas of need, such as the Duluth Public Library.

Kazel said the department has seen an uptick in naloxone use in recent months as a likely result of the distribution of the highly potent fentanyl.

St. Louis County Attorney Mark Rubin, whose office is prosecuting five of the cases, said of the influx of fentanyl: "This is serious and this is deadly."

"Certain states are having trouble finding the drug they normally would use for the lethal injection to take a life for capital punishment," he noted. "In lieu of the drugs they've used in the past, now they're turning to fentanyl because of the powerful and lethal nature of the drug. That is what these characters are dealing on the street."

Charged in the conspiracy are:

• Aaron Andre Reynolds, 36, St. Louis County, first-degree aggravated controlled substance crime

• Joshua John Wilding, 31, St. Louis County, two counts of first-degree aggravated controlled substance crime, three counts of felon in possession of a firearm

• Tymisha Monique Broughton, 28, St. Louis County, first-degree aggravated controlled substance crime

• Kari Ann St. Marie, 31, St. Louis County, aiding and abetting first-degree aggravated controlled substance crime, child endangerment, three counts of felon in possession of a firearm, possession of tear gas or stun gun by a felon

• Samuel James Nelson, 31, St. Louis County, aiding and abetting first-degree sale of more than 10 grams of heroin

• Jonathan David Polaski, 21, Douglas County, manufacturing or delivering more than 50 grams of a heroin analog, bail jumping

• Alicia Kay Robinson, 29, Douglas County, manufacturing or delivering more than 50 grams of a heroin analog