on the surface, there were haunting similarities. in april of 2010, 69-year-old dolores alliotts had been found stabbed to death in her burning home. she was a woman that was known to leave her house open. she did not lock her doors. it could have been a stranger from the street. >> reporter: a few months later, 74-year-old joan davis, a well known community activist -- seen here at a teaneck city council meeting -- was found strangled and stabbed to death in her burning home. >> we had always believed that the person who murdered joan davis was someone that she let into the house. >> reporter: and now, rob cantor had been found dead in his burning home -- also in teaneck. >> very early on we were looking at you know, could rob cantor's killer be the same killer in teaneck with ms. davis and in palisades park with ms. alliotts. >> reporter: the answer was unclear, at first. but detectives did have leads in the cantor case. a neighbor had reported seeing a