So I read through 1-9 last night, and I'm still trying to figure out the end of #7, and exactly who it was in Hawkeye's house. It looks to me as though Hawkeye actually KNEW the the person, and the dialog suggests that the other person knew Hawkeye fairly well - well enough to call him by his first name. That can be misleading, though, as Hawkeye's identity is public (which seems rather short-sighted of everyone involved - Ultimate Hawkeye is one of the very FEW characters in comics who actually had a reason for a secret ID). Tonally, the dialog actually sounds like the "doctor" in the beginning of #9, but Millar is not always good at establishing a character's unique "voice" - a lot of characters sound the same, in speech pattern
So far we know that the "secret" security recordings seemed to show Captain America, and it seems like there are two options there:
-- It was someone who LOOKED liked Cap.
-- The recordings have been altered. Between when the murders occur (sometime late at night) and when the forensics team is in the house (sometime during daylight), there is easily enough time for the security recordings to be altered. To be altered, someone had to know the "secret" recordings existed in the first place.
The first option (someone who looked like Cap) -
-- We're pretty sure it was NOT actually Cap (or at least not the guy we think of as Steve Rogers, Captain America, let's not get into Fury's sudden assumption that Cap is not actually Cap).
-- Who looks like Cap? I've seen suggestions that it was Hank Pym in his "Cap" suit, but for all Hank's jerkishness, I can NOT see him shooting a child in the back of the head. Shooting Hawkeye with tranqs? Sure. But not as a cold-blooded murderer. None of the "Anti-Ultimates" actually look like Cap, either, though.
The second option (the recording has been altered)
-- The recording wasn't electronically altered, it was never a correct image due to Loki's influence. I guess this is possible, but I don't like this option, it seems to go against the themes and tones of the Ultimates. Loki's influence has been through being a "mover and shaker" behind the scenes rather than direct, overt action.
-- Who knew the recordings existed? Fury. Probably Hawkeye. Black Widow is a possibility. Who could alter the recordings? Black Widow maybe, Hank Pym definitely. The recordings were not being actively monitored (or SHIELD would have known what happened real-time) so someone might have had time to get into a database somewhere.
-- If the recordings were altered, it means that the actual killer doesn't have to be anyone in the Ultimates.
So what is YOUR guess for who it is at the end of #7, given what you know from #8-9?