The Doomed Man was first seen attending a sermon by Jack. Later, the man is seen in obvious distress among the pews of the mostly-vacant church. The man, mortally injured with a stab wound in his abdomen, tells Jack that the Visitors are responsible, and hands him an envelope with an address, and asks him to attend the meeting there, bringing the envelope.("Pilot")
While investigating the case of his death, Sarita Malik informs Jack that he was on the FBI list for calling the FBI dozens of times over the years over a supposed alien invasion.
This man is one of the first known victims of intentional homicide by the Visitors, was presumably a member of the Resistance. He was probably meant to have attended the fatal cell meeting where Jack met Erica, but was stabbed prior, leading him to pass Jack the photographs in his possession.