Actually he saw wounds to support both not just the serrated blade. Later he thought a box cutter could have been used. IIRC it was on Libby.The ME originally thought it was a serrated blade not a smooth one like a box cutter, and he just happened to change his opinion conveniently on time to testify at the trial
Big difference.
It's all in the autopsy reports on here that have been posted many times.
If by conveniently you are suggesting bias I will respectfully disagree until I have factual information to support that.