She was saved only after her nephew visited her flat in Southwark, south-east London, on Christmas Eve and became suspicious when he got no reply.
Detective Inspector Tony Cottis, the officer leading the hunt for the attacker, said it was 'a particularly ruthless attack on a defenceless victim'. Had it not been for the relative's visit 'this may have been a murder inquiry'.
Police said the attacker pounced as the woman returned from a shopping trip on 22 December. She was found dehydrated and in a state of severe shock after police forced their way into the flat and rescued her. She was treated in hospital, but was discharged to spend Christmas with relatives.