Returning stolen property that has depreciated or become obsolete
Question

                A man works in an air transport company. He steals a tape-recorder. After 
many years he repents. Now, should he return the same transistor radio, or 
a similar model or its equivalent price, especially considering that the 
original model is not sold in the markets now?
Praise be to Allah.He must return the same piece along with an additional amount equal to the reduction in 
its value that has resulted due to its usage or the course of time. Of course it is to be 
accomplished in a suitable manner without causing himself harm. However if that is 
impractical or infeasible then he can give in charity an equivalent amount in the name of 
the original owner.