It's a pattern thing.
Let's take car guy and janitor guy. Car guy stares at, obsesses over, happy couples. He wants what they have, the happiness. His other obsession is watching pornographic videos of people dying. He likes watching people die.
I think there's a very good argument that this does not a killer make. In fact, I'd say there's a good chance car guy ISN'T a killer-in-waiting. But IF he's going to do something incredibly fucked up, the correlation of snuff-porn with his obsessions (especially since he apparently follows them home, and watches from outside, according to the pre-filer conversation AND owns a gun, that he recently bought for reasons unknown) seems to imply that he may kill. For kicks, for power, whatever. The pattern holds that death is his hook.
Janitor guy likse taking pictures of pretty girls, and thinking about them with knives involved. He likes taking these non-pornographic pictures and making them look as if the girls' throats are cut. We don't know why, but it seems clear that he gets off on the idea of girls bleeding. Girls dying. Thus, IF he decides to follow through on his fantasies (which, again, I don't think is necessarily true - pre-filer is not a good guy), he'll be slitting throats.
Roger, however, owns kiddie porn. Which, so far as I know, does not generally involve pictures of dead kiddies. If there were pictures of kiddie-snuff porn in there, or even kiddie-rape porn, we were never shown the evidence, or even had its existence implied. He also takes stalkery pictures of little girls. But he doesn't cut them, or shoot them, or whatever. The only thing we know is that he looks at them. Now, maybe when he looks at them he's fantasizing about chopping off their heads and putting them on stakes, I don't know, but no evidence is ever shown of that. Thus, the most obvious conclusion is that he likes to think about sexing little girls. Hence, if HE were to follow through on WHAT WE KNOW of his fantasies, he would sex little girls. Not, necessarily, kill them.
I don't think persecuting any of these victims is the right thing to do, and i don't necessarily think homicide is much worse, if any worse, than child molestation in many cases. But I do think Roger is outside the pre-filer's standard pattern. So if you side with Rebecca's thoughts, and think the pre-filer is choosing killer's correctly, then the natural assumption is that Roger is a killer too, and I don't love that it isn't really tackled. I want to revisit Roger in the future, and I don't want him to have killed, and I want Rebecca to struggle with her assumptions more: then, I'll be fully happy.
ETA: Also, what Allyson said.
I can't remember all of them, but IIRC, that was the case for everyone but Roger.
My assumption was that he was waiting to kill them, not waiting to work out if they were really appropriate targets.
Roger got rushed to market because of Rebecca's background.
I'd laugh if he was planting evidence, though.
I find it interesting how quickly Paul was to judge the S&M people but he had no problem seeing the line between 'potential' killer and killer.
I don't think the pre-filer's methods figured into that very last choice the 'potential' killer had not made yet. He decided they would for sure do it but then again killing seemed fairly easy to him. He was missing that 'thing' that stops most people 'pulling the trigger'.
If there were pictures of kiddie-snuff porn in there, or even kiddie-rape porn, we were never shown the evidence, or even had its existence implied.
I can see where showing kiddie snuff porn on network television might be a little problematic...
Sure, sure. But so would be showing kiddie porn, which is why we just got little snippets of titles.
You can
talk
about it though. They didn't. I therefore assume it wasn't there, because what else can I do?
I find it interesting how quickly Paul was to judge the S&M people but he had no problem seeing the line between 'potential' killer and killer.
I think he'd have some harsh judgments on Roger's fantasy life, I'm not sure that he thought S&M was criminal, just repugnant.
My assumption was that he was waiting to kill them, not waiting to work out if they were really appropriate targets.
I had assumed that part of his enjoyment was in killing them in the manner in which they would kill. Which means waiting for them to make their little murder kits or dig the graves, buy the gun.
Of course, if Roger's intent/fantasy was to strangle his victims, or suffocate them in some way, there's no need to buy a gun.
Personally, I never thought Rebecca's biggest fear was that Roger would kill little girls. She may have gotten caught up in the Pre-filer's view of things, but I think her biggest fear was just that he would eventually move onto molesting them instead of just watching, which she probably thinks of as worse than death, having lived with the consequences of a similiar experience (I assume) most of her life. To me, that's what that stare was from her at the end.
She knows what his future victims will have to live with emotionally and mentally, and I think part of her really wanted to tell Martin to shoot Roger just for that alone. Death is easy. Living after a crime like that being done to you, is not.
ETA: And I agree with the "Pre-filer rush job just to get at Rebecca" thing.
Remember the good old days, when Donnie Pfaster had to be called a "death fetishist," because the netowrk would not allow them to say "necrophiliac" on air? Good times, good times.
For the record, it's relatively rare for pedophiles to be particularly murderous. Pederasty has more in common with acquaintance-rape than with serial murder, on the whole. Which is not to say that no pederast in history hasn't eventually advanced to murder, but it's quite common to spend 30 years performing child-rape as a Catholic priest while passing in everyday society without the danger of a corpse being found.
Which factoid has minimal relationship with the episode, since it avowedly was mixing up serial killers with spree killers, and probably meant to boil it all down to "dudes what do bad things."