That man was present during the meeting that was organized by Crimelord Carl Grissom, after the declaration of war on crime that was launched by the new District Attorney, Harvey Dent.
He sat next to his boss, Jack Napier. After the meeting, he joined Napier on a mission to retrieve incriminating documents from Grissom's business front, Axis Chemicals. After the Napier Hood who cut into the safe with an acetylene torch stepped aside, that man opened the safe for Napier, and revealed that it was empty.
After the GCPD arrived to apprehend Napier, he returned gunfire with them.
He was never seen during the gunfight.