MILWAUKEE (AP) — Twenty-six people are accused in a large-scale drug operation that sent hundreds of pounds of cocaine from Puerto Rico to Wisconsin, according to a federal complaint.

Drug dealers used the U.S. Postal Service to ship the drugs to Milwaukee and send cash back to the U.S. territory, prosecutors said. The 227-page complaint unsealed Wednesday indicates millions in cash proceeds were sent to Puerto Rico, the Milwaukee Journal Sentinel reported.

Federal agents and local authorities began arresting the 26 who are charged Wednesday. 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.

The 26 defendants are charged with drug distribution, money laundering and conspiracy. Convictions carry a possible life prison sentence.

An investigation into the scope of the organization continues. Federal and state officials involved in the investigation scheduled a news conference Thursday morning to provide additional details about the case.