Is it obligatory to return ill-gotten gains to a non-Muslim, and what should I do with the things usurped from them, knowing that this might expose me to criminal harassment?

The questioner is congratulated on maintaining prayer and striving for repentance, and is given the good tidings that Allah accepts the repentance of those who repent. Theft is one of the major sins and is forbidden by Islamic law, whether the stolen property belongs to a Muslim or a non-Muslim whose life and property are protected. However, it is permissible to take the property of a belligerent non-Muslim as war booty. Treachery and betrayal are forbidden with both Muslims and non-Muslims, such as someone who enters the lands of non-believers under a guarantee of safety and then steals their property. Among the conditions for repentance from theft is returning the rights to their owners. This can be done in a way that preserves the repentant person's dignity without revealing their identity, such as sending the money by mail or appointing another person to do so.