Leo Wayne Cook has been described by an FBI informant as “the largest drug dealer” on the Red Lake Indian Reservation, allegedly trafficking heroin up through Indian Country despite a series of drug arrests between Chicago and Minnesota over the past two years.

The 33-year-old Redby, Minn., man was first stopped alongside his girlfriend and another friend more than two years ago after authorities found about a pound of heroin in their car on their way back to Minnesota from Chicago.

But a judge suppressed evidence seized from Illinois investigators and the case was later dismissed. Almost exactly one year after that search, Cook was again arrested with even more heroin in his car during a stop along a northern Minnesota highway.

Cook was back on the street after bonding out of jail a day later. And last month, an informant told FBI agents that Cook had just returned from Colorado with another load of heroin laced with deadly synthetic carfentanil — just as Red Lake officials began sounding the alarm about a series of overdoses on the reservation. Even that apprehension proved short-lived. Cook is again back at home, having won pretrial release from a federal magistrate judge.

Last month, federal prosecutors became the latest enforcement arm to try to detain a man who has so far successfully deflected charges that he is responsible for pumping heroin into Indian Country, and Cook is preparing to fight another legal battle in a case that could soon expand into conspiracy charges as heroin overdose deaths continue to surge across the country. While the U.S. attorney’s office declined to comment on the ongoing case, Cook’s attorney says the case is likely to raise a number of constitutional issues, again including possible challenges to evidence taken by law enforcement. Cook is charged with possessing more than 500 grams of heroin with the intent to distribute.

“He’s presumed innocent and we’re certainly going to make sure that his constitutional rights are upheld,” said Ryan Pacyga, Cook’s attorney. “We’ll know a lot more about the case after we have an opportunity to look at the discovery and see what the government’s next step is here.”

Cook and two others won a significant legal victory last year when an Illinois appellate court upheld a judge’s decision to throw out evidence seized during a 2015 traffic stop about 50 miles west of Chicago, long considered a key source of heroin for the Twin Cities market.

Kane County, Ill., sheriff’s investigators found about 400 grams of heroin, two loaded handguns, $8,000 in cash and marijuana flakes inside the car. But a judge ruled that the traffic stop was illegally prolonged because the K-9 sniff and search of the car came after a sergeant finished a written warning for Cook’s girlfriend, the driver of the car, and after he asked Cook about proof of insurance that was not required under Illinois law.

State prosecutors dropped charges last month after the appellate court upheld the suppression of evidence. By then, Cook was facing the federal drug charges in Minnesota that stemmed from an October 2016 arrest in Hubbard County.

Hubbard County prosecutors dismissed first-degree drug possession charges — which, like the charges he faced in Illinois, carried the potential for decades in prison — last July after learning that federal prosecutors were taking the case.

By this time, according to court papers, the FBI was unwinding details about Cook’s activities in Indian Country from informants and other cooperators.

According to an FBI agent’s application to search Cook’s car and home, one source told agents last March that Cook often stored “large amount[s] of drugs and money” at a Bemidji home he shared with his girlfriend and that he also used a hidden compartment in his car to ferry drugs around the area.

The agent also wrote that an informant told the FBI last month that Cook had also returned from Colorado on Dec. 1 with a supply of heroin purportedly laced with carfentanil, a synthetic opioid 10,000 times more powerful than morphine.

In search warrant applications, federal authorities pointed to recent increases in opioid overdoses in Red Lake, Bemidji and Beltrami County. Last month, the Red Lake Police Department issued an “urgent public health notice” after a person was dumped by friends at the Red Lake Indian Hospital. At the time of the Dec. 19 alert, surrounding reservations like White Earth reported responding to more than a half dozen overdose calls, two of which resulted in deaths.

Pacyga, Cook’s attorney, described Cook as a Twin Cities native who moved up to the Red Lake reservation in recent years. He said has been recently seeking higher education and work opportunities and will continue doing so as his case progresses.

“Suffice to say the federal magistrate has Mr. Cook right now on a very tight leash,” Pacyga said.