Anna could barely believe it when she saw Duke alive and well in Port Charles in 2012 and thought they could pick up life where they left off all those years ago. However, the man who looked like Duke turned out to be Cesar Faison in a mask (via TV Guide).
Anna was crushed, but then in an odd twist, it turned out that Duke really was alive and had faked his death and entered the witness protection program. Duke was even there for her as she tracked down a kidnapped Robin. However, Duke seemed to never learn from the past and started working for the mob again, according to Soaps In Depth. This time, he worked for Sonny Corinthos (Maurice Benard).
That’s when things went terribly wrong once again and Carlos Rivera killed Duke in a mob hit just after Anna had agreed to run away with him and leave Port Charles forever. Anna was so grief-stricken that she went against her own moral code and shot Carlos in cold blood.