To be fair, there's 'something' about identical twins that I find a bit creepy (not non-identical twins (obviously) writes the non-identical twin mother of non-identical twins).
Perhaps none of them did it?
Someone mentioned that there is some relevance in the fact that the young woman who was killed was an identical twin, i.e. information given to the viewer is rarely wasted.
To be fair, there's 'something' about identical twins that I find a bit creepy (not non-identical twins (obviously) writes the non-identical twin mother of non-identical twins).