According to Europol, the European drug market is valued at at least SEK 300 billion a year.
In a large European port, a customs officer can be offered one million kronor to let through a container without control.
- It is clear that there is corruption, it definitely does.
The feeling is that corruption is increasing, but then you should know that it is from microscopic levels in comparison with other countries around, but the development is still a little worrying, says Lennart Karlsson, one of Sweden's most experienced drug police and chairman of the Swedish Narcotics Police Association.
"Have loyalties elsewhere"
In Mexico, the police are permeated by corruption and links to the cartels.
The fact that the police are behind murders and disappearances on behalf of organized crime has been documented year after year by human rights organizations.
That is far from what it looks like in Sweden.
But Lennart Karlsson says that the Swedish police are also affected by the drug trade.
- There are certain things, certain sensitive matters that we do not talk about at all other than in a very small circle because we know that it also leaks from the police's activities.
That there is corruption in the police?
- Well, not corruption.
More like there are people who have loyalties elsewhere than just within the police.
Assignment review team has followed in the footsteps of the illegal drug trade from Stockholm's inner city, via brokers and Mexican cartels - all the way back to Colombian coca growers.
See the whole series
: "In the shadow of el Chapo"