Possibly, but he does not give me those "vibes". Part of this is because I think he needed the affirmation of his partner to carry out the crime. My guess is that instead of being described as "odd", "violent" or known to kill animals, the people who know DE will describe him simply as shallow, arrogant, and being an over all jerk.
I think that DE was trawling with no real purpose other than personal amusement when he befriended and manipulated the victim. Meeting NK, however, amplified his lower level evil tendencies. Likewise, DE did the same for NK. They then "fed off" each other to the point where they were willing to commit murder.
In short, had DE never met a person willing to affirm, encourage and assist in his contemplated crime, DE's action would have been to fly into a rage, calm down call his father, and utter the words: "Dad, I need a lawyer". Of course, I could be wrong and DE may have been willing to commit the crime alone, but his lack of criminal history and lack of obvious prior violence, and the fact that he took on a partner makes me think that he needed this partner for support and to exacerbate his evil tendencies.