IMOO There is a correlation (psychologically) between exhibitionism and threatening with an axe/hatchet...both phallic aggressive attempts to threaten and shock, rendering the victim momentarily confused, distressed, ...robbed of presence of mind to feel a sense of control over the interaction. Exhibitionism is a violation of unspoken but understood rules of normal interpersonal engagement. DN's prior history of exhibitionism and his recent arrest for threatening with an axe suggest underlying acting out of power dynamics in interpersonal engagements. It is no surprise that exhibitionism frequently escalates to more serious forms of acting out control/power dynamics. What one had to endure passively gets acted out actively, With this in mind, and with the other details of DN and the Delphi murders, I can see him being the one.