Etype 3. Because everybody knows that only unhealthy e-3 acts like this.
He's not a serial killer however, because the media doesn't refer to him as Robert Allen Durst, and anybody with a college education knows that only serial killers have middle names in the media.
I'm having a hard time determining Robert Durst's MBTI type, because without an exact birth date I can't very well look up his astrological birth chart.
P.s., I hope this OP is in compliance with the new FAQ!