Two things that definitely arent normal -
1 = A woman screaming if a man attempts to kiss her.
2 = A person gets strangled to death for screaming
As you say above, most men/women not wanting to be kissed by another person probably would react by saying "what the **** do you think your doing ?? - get out of my flat at once...", which leads me to suspect that the truth is he may well of attempted to kiss her before being rejected but then went on to force himself onto her, causing her to panic & scream fearing rape, he did hold her mouth, he did throttle her, he did murder her. He couldnt stop himself, he killed her before he could rape her. The adrenaline took over for those fateful moments, if she had stopped screaming he probably would of raped her - he did say he let go of her mouth, but she kept screaming, this was the point where he could of walked away & that would be that, but it was rape or die in my view. But he couldnt rape her screaming her mouth off, & thats why he wouldnt let go of her throat.