In a case which has gripped the US and shocked the world, the investigation into the Idaho university murders continues.

Ethan Chapin, Xana Kernodle, Madison Mogen and Kaylee Goncalves were all stabbed to death on November 13th last year.

The suspect, Bryan Kohberger, has been identified, but still, there is no apparent motive and so many unanswered questions – with one in particular, why?

This is what you need to know…