Does anyone have any idea about how he killed her? Pushed her down the stairs, or bashed her or strangled her? can't imagine how that happened.
only Borce knows... and whoever else was there at the time.
In the end, it will be irrelevant. The law will take the position that Karen did not co-operate in her own death, as is the normal human reaction, and that her life was taken illegally and with force from her. How it was done, how long it took, what was used, who did what, when it happened , even why it happened, these things wont matter that much in law. The fact that it did happen is all the law really requires. .
The Vic Pol don't have to come up with a motive, or a method or the means, only the unarguable fact that Borce saw her draw her last breath, which is why it is a charge of murder, not manslaughter, not negligence, not carelessness, not accidental.....