During the bomb threat the Joker made against Gotham City's hospitals, fifty people were kidnapped on a school bus used to evacuate the same hospital that, at that time, held Two-Face. One of these victims was Mike Engel, a member of the Gotham News Network.
Engel was then used by the Joker to deliver a threat against Gotham City as a whole, stating that the city was now property of the Joker, and anyone who did not wish to be part of the madness should leave. Furthermore, anyone who took any of the bridges or tunnels to escape the city limits was "in for a surprise." The validity of this threat was never proven, but due to the Joker's history of "being a man of his word", was taken at full value.
After reading the Joker's statement on live television, Engel was placed as one of the thug decoys in a building. After Batman told him to stay down, Batman stopped the SWAT team who were going to apprehend or shoot the hostages, believing they were the Joker's thugs.
Mike Engel was the first one saved along with all the other hostages during the crisis.