PAW PAW, Mich. (AP) — Authorities say nine people face felony drug charges as the result of an 18-month investigation into the illegal distribution of heroin, cocaine and marijuana in Van Buren County.

The Van Buren County Sheriff’s Office announced Wednesday that the probe began in April 2014 and focused on the illegal distribution of drugs in Hartford, Hartford Township and Covert Township.

Seven people from were arrested Wednesday on charges of sale or delivery of heroin, cocaine or marijuana. Detectives plan to seek additional charges against two of the suspects in connection with marijuana found during searches at their homes.

Investigators obtained warrants for two other suspects on charges of sale or delivery of cocaine in connection with the case. They hadn’t been arrested as of Wednesday afternoon.