I don't think any useful discussion can be had using this case as a case study without knowing if victim and perpetrator had prior communication or if they were known to one another.
Mutual friends I found on Facebook suggests they did...
We could talk about Sven Badzak who had gone out to the shops to pick up some orange juice and was randomly killed a few weeks ago in London but no one would know what you are taking about.
We could discuss the fact she's a pretty, young white woman.
We could discuss why 99% of the world who doesn't live in London is going on about this story when there are more relevant things at home.
We could discuss how the media and politicians are already telling us how to feel, how to act, what to think when all the information isn't out.
Mutual friends I found on Facebook suggests they did...