The police arrested three men in the Rastatt district who are said to have sold drugs to hundreds of people on the Internet.
The alleged main perpetrators, aged 26 and 29, are in custody, as the public prosecutor and police announced on Friday.
They are accused of drug trafficking. A 56 year assistant had confessed and was released again under certain conditions.
The investigations were initiated by officials from Lower Saxony who deal with crime on the Internet. After eight months, the officers struck last week.
Two searches found around 30 kilograms of marijuana, 1.7 kilograms of opium, as well as cocaine, ecstasy and several marijuana plants.
The investigators also discovered everything for a functioning online shop: stretchers, vacuum sealers, precision scales, packaging and shipping materials as well as records of drug deals.
According to the investigators, the drug marketplace was on the Darknet, a specially protected, anonymous area of the Internet.
The drug seized has a value of at least 150,000 euros.
Hundreds of customers are now being investigated, it said.