DULUTH – Authorities in northeastern Minnesota have busted a major heroin ring that they believe spread kilos of the drug into local communities, fueling a troubling opioid crisis, law enforcement officials announced Thursday.

A dozen defendants, many of them from the area, were indicted in federal court on charges of conspiracy to distribute the drug and other varied counts. Seventeen additional defendants face felony state court charges related to its sale. More arrests are expected.

Authorities allege the ring moved heroin from Chicago to the Twin Cities and then north to the Twin Ports of Duluth and Superior, Wis., where it was distributed through a network of conspirators.

The group was responsible for a "significant" portion of the drugs brought to the northeast part of Minnesota, said Jeff Kazel, commander of the Lake Superior Drug and Violent Crime Task Force. Although authorities declined to estimate specific quantities, Kazel called the group "a big player."

Opioids have wreaked havoc in northeast Minnesota in recent years. St. Louis County, which stretches from Duluth to the Canadian border, had the second-highest rate of opioid-involved overdose mortality in the state from 2011 to 2015, with 10.7 deaths per 100,000 people. Neighboring Carlton County had the highest rate with 12.4 deaths. The state average was 5.7 during that time.

Authorities credited the bust to strong cooperation among federal, local and tribal law enforcement agencies, including the ATF, DEA, several local police and sheriff's offices, and the Lake Superior task force.

"This network has been responsible for bringing a near-constant supply of highly potent and highly addictive heroin into the city of Duluth and the surrounding communities," said U.S. Attorney Greg Brooker, who traveled to Duluth to help make the announcement at a news conference.

Brooker pointed to a large board depicting photographs that alleged ring leader Carlos N. Coleman, 33, of Apple Valley, had put on social media, including wads and stacks of cash and a gem-studded Rolex watch.

"He certainly showed off the profits he made from the heroin he distributed here in Duluth," Brooker said.

An attorney for Coleman couldn't be reached.

St. Louis County Attorney Mark Rubin said bringing down the network took "more than a year of investigation and I think about 28 controlled buys" from one defendant alone. Law enforcement aimed to trace the drugs back to the source, he said.

"We're going up the ladder," he said. "We're going back to Chicago where this garbage is coming from."

Duluth Police Chief Mike Tusken called the ring one of the largest he's seen in his career, and said he believes a total of nearly 40 people could be arrested by the time officers are finished investigating.

He cited sobering statistics from his city alone: 323 overdoses in the past six years, and 44 deaths. Since officers started carrying opioid antidotes in the past two years, police have saved 56 lives, he said.

"We are doing everything we can to interrupt, intercept the source of supply of these deadly poisons before they reach the streets of Duluth," Tusken said.

He warned other drug dealers: "If you're peddling poisons to our people, we are watching you and we will hold you accountable for your actions."

The DEA established a formal relationship with the local task force last year, Rubin said, becoming a model for other areas in the country.

Together, they were able to bring down criminals who were "providing only more water to our fellow citizens who are drowning in the sea of addiction," Rubin said. "Today we turn the tide."

Pam Louwagie • 612-673-7102