Complex sentence: Just before that goes any further, Cale then begins to interrogate Raphelson about how he conspired with Walker to orchestrate the attack, which he then proves by having Finnerty dial the call-back number on Walker's pager, the source of the updated launch codes.
Split into simpler sentences: Just before that goes any further, Cale then begins to interrogate Raphelson about how he conspired with Walker to orchestrate the attack. He then proves by having Finnerty dial the call-back number on Walker's pager, the source of the updated launch codes.