Please note the forensic department of any investigation agencies can still solve the case, even if other evidences have vanished(the murder weapon, motive,confession...etc)
The forensic department should use ultraviolet light to scan the cleaned room where late Arushi was found to pull out evidences indicating uncovered finger prints..stains.. foot marks etc., Also they can try and look for some stain marks etc., below the cot legs... look for evidences below the door crevices... window sils.. above the fan in her room...ask for records from the mobile company.printout of sms of her father, herself and others involved or suspected of invovlement.. photographs taken by the police... and place it before an intelligent detective, who can analyze impartially how the murder was carried out... then other pieces of the puzzle will fall in place.
The Killer will face his karma for sure...
My only prayer to the little girl who is no more, is MAY HER SOUL REST IN PEACE... HOPE SHE HAS A BETTER LIFE IN HER NEXT REINCARNATION...