Thank you! Yes you are so right that it could be so many reasons why they decided it was a homicide.
My point was, that I find it very unlikely, that it was just one injury, that could also be because of she just fell ( the same that he pushed her and it was an accident of sorts).
So I think the "oh he just pushed her away and she fell down and hit her head and he panicked and ran"- scenario is propably not the case as I hope they are at least sure (to some extent of course, as life is always unpredictable) when announcing it was No accident. So let's be honest, whoever it was, likely Brian, it was a clear killing. Maybe impulsive and whatnot but the killer knew it would not appear as anything else. MOO OOMB