OK, take a look at the NTSB animation:
YouTube - Colgan 3407 NTSB Animation with Sound
When you say the Captain "allegedly" made an error, what exactly do you mean?
The Captain crashed the plane, independently of the fact the F/O was also trying to
help him crash the plane. Look at the speed tape (which reflects stall speed for existing flap settings, not the settings he wished for), look at the power levers, and look at the elevator and aileron inputs throughout this sad evolution.
IOW, he F/O was trying very hard for a Best Supporting Actress Oscar in this horror movie, but he was notnethelss the lead actor, and the director. Considering his actions in the years prior, and his (alleged) falsifications of records, I'd say he wrote the script too.
I stand by my assertion: this accident had little to do with fatigue. You're mistakenly assuming that even if she had rolled out of bed all nice and fresh, she would have the skills and experience to overcome his desperate attempts to crash the thing. Looking at her act of retracting the flaps, even once the adrenalin flowed... I just don't see it. In other words, her being tired was not the accident link that needed to be broken, her presence and was the accident link.