I like Dr. Lee. His particular expertise is blood drops, spatter, pooling etc. He pretty much wrote the book on blood scenes. I remember one case in which he was involved where the wife disappeared and there were many puzzling issues about her disappearance, one being a stain of blood in front of the garage door.
Lee looked at photos of the house, noticed a missing window shade that no one else had thought important and concluded that the wife was wrapped in the shade and slid out of the window to the ground, exactly where the blood stain was located. IIRC the shade was found with the body.
Lee testified at one of the most famous cases here where 2 men were on trial for killing the wife of one of them. They both admitted being in the house the night she died, but neither would confess nor rat out the other. Lee unscrambled the blood patterns of the house and the spatter on the shirts, pants, walls, ceilings, doors, etc., and determined that both men had taken swings at the wife's head with a baseball bat. Neither would confess, both went to jail for life.
If someone testifies in hundreds of trials, there will be something in the past that went wrong and will be used to impeach the expert. No one is right 100% of the time.
He wasn't called to the stand for SP because he couldn't help SP with his testimony. It is that simple. What Lee had to say would have helped to convict SP.
If I had to hire an expert, I would not hesitate to call upon Lee. It doesn't matter who is paying for his services, which are probably between $5K-$10K - depending on the time he spends on the case but unless KC has been declared an indigent, the State is not paying for his services.
I am guessing that Lee doesn't want Baez with him during the examination of the car to avoid any appearance of tampering, because I can not imagine representing KC and NOT seeing that car for myself.