Since the 38 stabs were first, I don't understand why Martha wasn't screaming her head off, do you?
And since many of the stabs were through her lungs, she would almost certainly have been spraying a mist of blood, if still breathing (which I don't remember the doctor's report saying anything about). Is this evidence that she was already dead?
A question I raised very early in this thread is that of the question of 2 weapons. I believe that Ive read that multiple stab wounds with more than one weapon is often result of the failure of the first weapon used and another weapon being chosen based on ready availability, not because the attacker had 2 weapons from the start.
Unless we have some wound that reflects that the smaller pen knife broke during the attack, the likelihood that the same offender used another weapon that was not available at the scene is lessened.
We also have evidence that a soldier questioned near the site of the attack said he was waiting for a buddy who went off with a girl, so it seems soldiers were travelling in pairs that night. Which is a reasonable explanation for 2 weapons being readily available at the scene.