Best part about cutting the head off a snake that big is there are probably a few million other Americans who had strong cause to want the guy dead too. So that's not gonna single you out.

No money changed hands, no co-conspirators to give you up. If you were smart enough to keep the entire thing in your head and weren't talking shit last week near any form of telecommunications about how the dude has to die whilst googling "how to buy suppressors" and "how to avoid CCTV cameras" (that shit is interesting though, and learning is a noble recreational pursuit, but best done far removed from any intent to commit an actual crime), then there is no easily searchable digital footprint of your intents.

If all that is true then just being able to evade immediate apprehension, reaching a large unsurveilled location to change your appearance, and leaving that location under a different veil of anonymity to travel far, far away before touching anything personally identifiable could theoretically leave them with very little to go on to find you. Especially so if everything you used both before and after that first change are destroyed/gone forever so there is nothing to differentiate you from the thousands of other people who left the park that night even if they did come to your house and rifle through your stuff.