William Peterson, after lengthy negotiations with CBS, has finally agreed to appear in the 2008-2009 season of CSI (the show's 9th), reprising his role as Gil Grissom.

However, he will not appear in every episode and it is still unknown exactly how many episodes of the season he will be in.

Furthermore, this contract is only good for one year, so if the show lives on longer, it will have to be renegotiated.

Source: E!Online