White doves

My sister has breast cancer and yesterday was her birthday so my father decided to buy her a beautiful white dove so she can pray with it and release it. WELL... my sister prayed with it, caressed it and then released it. HOWEVER, now the dove won't leave, this all happen yesterday afternoon and the dove was almost eaten by a cat, and managed to fly away to my sisters roof. Hours later some thing was pecking at her dining room table and they opened the shades and the dove was trying to get into the house through the window. And this morning my brother in law opened the shade to the master bedroom bathroom(their room) and the dove is just sitting there. And when my sister went to him, it looked at her like crazy. 

Does anybody know what that means? Why won't the dove leave?