MILWAUKEE (AP) — Federal prosecutors have charged 37 people accused of sending cocaine and other drugs from Puerto Rico to Wisconsin and elsewhere in the country using the U.S. Postal Service, authorities said Thursday. The United States Attorney’s Office in Eastern Wisconsin said the drugs were sold in the state, as well as cities in the East Coast and Southwest. Prosecutors declined to name the cities. At least $1.3 million of the proceeds from the drug sales was sent back to Puerto Rico, prosecutors said in a 227-page criminal complaint unsealed Wednesday, the day the arrests began. U.S. Attorney Matthew Krieger said over 300 officers from Wisconsin and Puerto Rico executed warrants to arrest 32 of the defendants, who they believe belonged to two drug trafficking operations, authorities said Thursday. One of the investigations, dubbed “Operation Island Hopper,” resulted in 26 people being charged with trafficking at least 5 kilograms (11 pounds) or more of cocaine as well as heroin and fentanyl. They were also charged with money laundering and conspiracy to commit money laundry. Each faces up to 10 years to life in prison if convicted. Four of the suspects remain at-large. In a second operation, a grand jury indicted 11 defendants with conspiracy to distribute 100 grams or more of heroin and 40 grams or more of fentanyl in Milwaukee. Ten of the defendants have been arrested. The investigation, which opened in 2018, revealed drug dealers in Milwaukee were also receiving heroin and fentanyl. The U.S. Postal Service had intercepted a parcel containing 3 kilograms (6.6 pounds) of cocaine from Puerto Rico. It’s unclear exactly how much cocaine came into Milwaukee through the mail, but prosecutors suspect it could have been as much as hundreds of pounds, said Kenneth Gales, a spokesman for the U.S. Attorney’s Office. Wisconsin Attorney General Josh Kaul praised the diligent work of investigators for building an extensive case over a year instead of prosecuting a single case when a package of drugs was seized by the U.S. Postal Service. “This is a case that investigators worked at and worked at to develop into a much larger-scale case,” Kaul said. Last year, over 370 people died of drug overdoses in Milwaukee County alone, double the number from 10 years earlier, Krieger said. “There’s still far too many lives being lost. This suffering is fueled by criminal organizations that exploit this suffering for their own profit,” Krieger said. Some defendants made their initial appearances Wednesday in federal court with the assistance of translators. It’s unknown whether they have attorneys. Others arrested in Puerto Rico are making their first appearances in court there. The criminal complaint says that when the drugs didn’t arrive as expected, suspects called the U.S. Postal Service with tracking numbers to inquire about where their packages were. The search warrants executed in Milwaukee and Puerto Rico resulted in the seizure of about 15 kilograms of cocaine, at least 50 grams of heroin and 80 grams of crack cocaine. Authorities also seized 35 firearms and about $267,000. Another search warrant in Milwaukee yielded 800 grams of black tar heroin and 200 grams of fentanyl. The U.S. Drug Enforcement Agency and several police departments from southeastern Wisconsin assisted in the investigation and executing the search warrants.