"I had a black out," the man told police after being detained for being drunk and disorderly the same evening.
The man had collected the drugs from a box at the Silja Lines ferry terminal in Värtahamnen the day before on behalf of a 44-year-old known criminal with links to the drugs trade, according to a report in the local Länstidningen Södertälje.
The man initially stored the drugs at home, but as he didn't want to leave the valuable commodity out of sight, he took the bag with him when he went shopping at his local Ica supermarket.
The 58-year-old's absent mindedness led to consequences far beyond his own situation after the find put police on the trail of a Europe-wide drugs operation,
As a result of the wider investigation the 44-year-old man was sentenced to 12 years imprisonment and a further two foreign couriers received sentences of nine years apiece.
The 44-year-old Stockholm man was previously known to police and had been released from prison on probation from a prior drugs conviction in November 2009.
The 58-year-old man has appealed his sentence and his case is thus due to be considered by the Svea Court of Appeal.