was he hoping that they wouldn't be able to track him down?
Almost certainly so.
And this doesn't mean he wasn't innocent of any crime.
If you'd just had to kill someone who was trying to kill you, and you knew the scene looked absolutely horrible for you, and didn't think anyone would believe the truth... you can't see yourself possibly just making a run for it?
Rather than cross your fingers that the justice system and 12 random retards off the street are going to be rational? That the prosecutor isn't going to withhold evidence from your defense attorney (or public defender if you can't afford a decent one... even worse)
Or, if it's a minority that you killed... that the media and public aren't going to get so hyped up on a narrative that the facts will cease to have even the slightest chance of mattering?
Shit. I could easily see myself making a run for Mexico or something in a situation like that. Get an old fishing boat... fix it up... take tourists out in it... I don't think that's too much to ask.