JEFFERSON COUNTY, Colo. (CBS4)– After months of investigation, the West Metro Drug Task Force has arrested four people in connection with a heroin selling business.

The drug task force has been investigating the case since July.

The suspects, Julio Cesar Gandara-Quinones, Gustavo Adolfo Valdiva-Garcia, Reynaldo Anguiano-Valdivia and Acela Davalos-Castanedo, are accused of selling about a half pound of heroin on a weekly basis.

Acela Davalos-Castanedo (credit: JeffCo Sheriff)

They targeted parts of Denver and Jefferson County, sometimes to buyers in their teens.

Reynaldo Anguiano-Valdivia (credit: JeffCo Sheriff)

Gustavo Adolfo Valdivia-Garcia (credit: JeffCo Sheriff)

All the suspects are illegal immigrants.