Jeffrey McGuigan, or, by his own preference, "Magoo", is an internet millionaire, and computer wunderkind. McGuigan almost turns Castle into an instant murderer, due to his philistine lack of sensibilities about mixing root beer with a $26,000 bottle of 135 year-old scotch. He shows many of the classic symptoms of "too much too soon" during his brief appearance in Last Call, but is never a serious suspect, nor does he get pulled into the station.