Is the amount of coverage a murder receives proportional to how rich or famous the victim is?

Yes - to an extent. If the victim or family member/friend of the victim is recognised by the public, more papers will be sold! They also potentially are in a better position financially to speak to the right people and do the good work that will better their public image (cynical i know!). The other dependent would be the manor in which a murder took place. If it was an unusual story, one which begs the comment, ' it could have been any of us', this is likely to get bigger coverage too. Knife crime is now so tragically common that i am not surprised to see another victims story on the news. Many more stories will cascade from the case is there is a famous face or name involved at some level.