The Katiska trial, which began at the end of January, is nearing completion in the Helsinki District Court.
Monday is the last day for dealing with a case before the final statements, for which four part-sessions have been set aside.
Businessman Niko Ranta-aho and former gang leader Janne Tranberg are suspected of leading a league that smuggled significant quantities of various drugs to Finland.
There are more than 50 defendants in the case.
IS is following the trial at the Helsinki Courthouse.