Is it obligatory to return stolen goods to their owners, knowing that doing so might lead to great harm?

Repentance is achieved by returning what was stolen to its owners, and thereby one's responsibility is cleared. It is not a condition to inform them of the theft; rather, the aim is to deliver the stolen item to them by any means. Repentance is not complete without this. Whatever harm is anticipated from informing them, it is lesser than the disgrace of the Hereafter.