Possible explaination, makeup to cover.
Example, on the now canceled show charmed, when they first started out you couldn't tell they had tats because makeup covered them (back then the network thought it taboo to have women on tv with them) as the show went on they were revealed.
As to CSI it could be that she wears temps or it could be that occassionally she has them covered up so as to do something different. I never paid attention if she had one or not lol.
Example, on the now canceled show charmed, when they first started out you couldn't tell they had tats because makeup covered them (back then the network thought it taboo to have women on tv with them) as the show went on they were revealed.
As to CSI it could be that she wears temps or it could be that occassionally she has them covered up so as to do something different. I never paid attention if she had one or not lol.