Personal rights are valid for non-Muslims, too. If you have violated a non-Muslim’s right, you have to compensate for it and seek his forgiveness. As one’s rights belong to him only, it is essential to respect those rights whether he is Muslim or non-Muslim. Someone who wrongs another one is going to be called to account for what he has done, no matter who he is.

According to Imam Azam and Imam Muhammad, it is impermissible for a Muslim who lives in a non-Muslim country to defraud Muslims and to steal or to usurp their possessions, as well as non-Muslims because Islam is a religion of tolerance and virtue and it prohibits fraud, betrayal and immoral and disgusting things everywhere. 

And if one goes to Europe and finds something that belongs to the state or an individual, he has to return it to the owner. (Hidayah v.2, p.66).