If your friend is SERIOUS about wanting/adopting this kitty...here's an idea. (We had to do this to gain legal custody of our cocker.)

Turn kitty over to the pound. If the owner wants her back bad enough, they'll go looking for her. If not, have your friend adopt her. Your friend will then have legal custody.

We did this with our cocker...her original owners didn't want to sell her/give her away, but they didn't want to keep her in the yard/house either. So, we loaded her up in the car took her to the pound. The 'real' owners never called/came for her, so we adopted her the first day she was available. (Waited for 5 hrs before the pound opened--just to make sure we got her! lol)