banfield was an agent for the criminal division of the irs. >> we know brandon banfield and julianna s. the family au pair were involved in a romantic relationship at the time of the murders. >> prosecutors say that fall, banfield began plotting to kill his wife, christine. court documents stating brendan banfield expressed to perez magalhaes his desire to be rid of his wife and soon thereafter began planning to kill his wife. authorities say banfield enlisted his lover, the au pair, to help, taking the then 22 year old to a gun club where perez magalhaes told investigators he taught her how to shoot. hey, paul or jose on the day of the murders, police responding to a 911 call came across an appalling scene. the original story is sometimes extremely helpful. >> what ends up being the inconsistencies in their stories as to what actually happened at the scene? it's all really important to capture. >> initially, perez magalhaes told police an intruder stabbed christine multiple times and banfield shot him in an attempt to save his wife's life. >> he started stabbing her. brendan, i think

. >> we know brandon banfield and julianna margulies. the family