

There are the obvious mentions of this theme and then there the indirect ones. We begin with a Eulogy for a dead girl. It does not really matter what she has died for, just that she is dead. We then move to the morgue and then to a grave and we find out we are dealing with a death fetishist, a guy who thrives on the hair and nails of dead people which when one comes to think of, is quite ironic, since in both cases, most of the hair and nails of a live person are actually already dead cells and cutting hair and nails while we are alive does not cause us pain, yet for the death fetishist what gives him the thrill is the fact that the person from whom those 'trophies' are taken is dead, and that he knows he/she is dead.
Then there are the other hints related to Donnie Pfester the death fetishist - the guy who chooses to work in a morgue to be close to his fetish, but when he cannot work at such a place he works as a deliverer of frozen food, the same food in which he later on put a cut-off finger of a prostitute, not to mention that the whole concept of cold and frozen is related to death and the condition a dead body is in - so Donnie himself is a cold person, his house is freezing cold, he immersed the bodies in cold water (Scully said it concealed the time of death - but to what end?) and again - he worked in delivering frozen food and got that job after the previous delivery guy died.... He surrounds himself with death by living in the his dead mother's house and covering his bed and room with flowers used to cover graves. Then we also get other opinions about death in the form of the explanation of Frued's death wish in relation to fairy tales for one (the mythology lesson), and then we have Scully's own explanation of death in the autopsy scene:
"Death is a recorded event. For reasons natural and unnatural when a body ceases to function the cause and the effect can be clearly reconstructed. The body has a story to tell...... It may be an irony only understood by those of us that conduct these examinations, that death, like life itself is a drama with a beginning, middle and end."
I don't recall Scully ever giving us such an explanation. She herself was consumed by her sudden fear of death and kept seeing Pfester as a kind of Lucifer, keeper of hell.

The main message of this theme is given in the end by Mulder, as he points out how ordinary Donnie Pfester appeared, and how we prefer to accept "true" unordinary things like aliens and so, and cannot accept that there are real 'normal freaks' living amongst us. It is the fact that a person who may appear as normal as anyone can actually be a fetishist or a psychotic murderer, which scares us. We are scared, 'cause it could be somebody like ourselves...
The theme is repeated a good many times in a number of ways:
You have the prostitute's reaction to the freak parade she was given as a
line-up: "He was ordinary. He didn't look like no freak!". It was impossible
for Bocks to accept that. Even after the prostitute's remark, the first
suspect he brought in was a guy with a series of assaults, and one has to
notice the freakin' out of the 'assaulter' himself when Pfester asked him
what the FBI were questioning him for: "They thought I was some freak,
digging up corpses!"... no... he's perfectly normal. He does the most
normal human and rational thing - he only assaults women...
Bocks mentions "the kid from Milwaukee" referring to Jeffrey Dahmmer (sp?)
who murdered and carved up a bunch of kids. He said that nobody could
believe this could happen. We refuse to accept such abnormalities among us.
Then Scully says in her profiling report of the death fetishist that the
murders that the fetishist eventually performs take the attention away from
the motive which people dare not imagine. That it is easier to believe in
the existence of aliens than in a "cold blooded monster who can pray on the
living to scavange from the dead". We prefer to focus on what we find
reasonable, like a 'regular' murder, but we cannot accept that a murder can
be done just for the purpose of extracting the hair and finger nails.
Then again we have the discussion of myths in Pfester's mythology lesson:
"Their [the myths'] deeper purpose is often to explain or make fanciful,
desires, wishes or behaviours that societies would otherwise deem
unacceptable."