Complex sentence: At the meeting place, Nathanson is killed by Bierko's henchmen in the 3:00PM-4:00PM episode, not before he gave Bauer a computer chip with information about the canisters.
Split into simpler sentences: At the meeting place, Nathanson is killed by Bierko's henchmen. Just before dying, he gave Bauer a computer chip with information about the canisters.