I have a question:
When Peter steals the laptop and Finn finds it and resells it and Paul, who thinks the laptop belongs to Finn, buys it and Peter finds out that Paul's laptop actually belongs to Peter. Can Peter ask for his laptop back now?
Never purchase in good faith in the event of theft
You mean Finn will find out?! Bad Faith After Buying? Luckily, it can stand there because it is never possible to buy things that have been lost in good faith. Only for money and securities.
He can demand surrender according to 985 BGB.