I think a curious thing about this case is that while a romantic relationship gone wrong looks a high likely motive, the act, and its aftermath, were also very likely carried out by more than one person, and with meaningful precision and planning. So this probably wasn't a typical 'crime of passion' carried out by one person in a temporary emotionally agitated state (those murders usually get solved within 24 hours to be honest). Others agreed, probably in advance, that it was the right course of action, and planned and executed their roles accordingly, with pretty impressive competence.