In Poland you can be temporary arrested for 3 months.

Afterwards, the court can prolong it for another 3 months.

Afterwards, the court can prolong it for another 3 months.

Afterwards, the court can prolong it for another 3 months.

...

It can go on for a while. It is called "extractive arrest" and it is meant to get suspect to admit when there is no evidence. It can go over 4 years and even some outliers are 9 or 12 years.