That's an interesting view.
Can you expand on how the victim in this case would have had to act in order to prevent her own unnecessary or accidental murder?
And how in that case, would she have walked out of the situation alive, and what the murderer's expectation was with regard to his own safety and ongoing freedom as she left?
To start - I'm not a criminal or a criminologist so this is all my opinion.
Firstly, he has been a sexual offender for some time and has been caught in some cases and in the balance of probability has not been caught in others.
This day he intends to sexually assault a young girl, she doesn't know his name, or real name, bearing in mind he is already on the run from another sexual assault so what does he have to lose.
Maybe he intends to lure her to the garage, succeeds, goes for what he wants but leah is able to defend herself more vigorously than he expects for such a small, young woman. A struggle ensues and Leah is killed accidentally.
To my mind it's possible, that he was close to finishing the work at this property, had gathered some cash in hand for the work and was ready to head further afield on the run. This would be his last opportunity to impose himself on a girl he's seen a few times and he takes it.
I don't expect that he had any thoughts on his ongoing freedom beyond the situation he was already in, he's already on the run so it's nothing different for him.
Criminals like this seem to have poor impule control and his factoring of risk vs reward is obviously totally skewed.
I hope that covers what you've asked, I get sidetracked easily.
Eta - how she walks away... she complies, doesn't fight. I'm not saying this is OK or remotely close to it, but in this scenario she complies and if that's his sole intent then she lives. But that's a huge thing to expect.
Further edit - because I missed a word and said I am a criminal (which is not the case)