Wouldn't they have checked her fingerprints anyway? And what about the dead son's stabbed body??
I mean, to see if she's really who she claims she is...?
And who are we supposed to believe killed the son? Her prints are all over him and the murder weapon still sticking in him! Surely the house didn't burn down to ashes...
Plot holes to drive a truck through...
Damien Thorn's sister meets Hannibal Lecter... - but in a silly way I actually enjoyed it - you just shouldn't think too much about logic and realism, just enjoy the ride...