Necroxxx is exemplified by the following words:
Necrophilia, also called thanatophilia or necrolagnia, is the sexual attraction to corpses. It is classified as a paraphilia by the Diagnostic and Statistical Manual of the American Psychiatric Association. The word is derived from the Greek words: νεκρός (nekros; "dead") and φιλία (philia; "love").
The dictionaries have a more complete definition:
nec·ro·phil·i·a (nkr-fl-) also nec·rophi·lism (n-krf-lzm, n-)
1. Obsessive fascination with death and corpses.
2. Erotic attraction to or sexual contact with corpses.
Hence, necrophilic and necrophiliac.
The word is seek is probably necromania
necromania: nec·ro·ma·ni·a (něk'rə-mā'nē-ə, -mān'yə)
n. An abnormal tendency to dwell with longing on death.
Hence necromaniac, a person who indulges in necromania.
Apparently, Necromania is also the name of a porn movie.
If you are willing to coin a new word, it could be necro-centric.
If you don't mind being sarcastic, then coin the word necroholic, addicted to the subject of the dead.
Other necro words are: necromancy, necrology, necrological, necrologistics, necrophoresis.
Furthermore, the consumerist society that envelops Siskind results in his necrophiliac/necromaniac/necro-centric viewpoint of his surroundings.
If I were you, I would use necro-centric.