"Remember the only expert produced by CBS is a handwriting expert."
Other threads have mentioned using Photoshop to "age" the forgeries. Maybe they pasted in an authentic signature.
You don't even have to get that fancy. Just print your forged document, literally paste on (i.e., with glue) a signature snipped from a real signed document (or a photocopy of one), then photocopy your glued "frankenstein" version. Voila, a copy with an "authentic" signature.
This is why signature analysis must be done on *originals*, not on *copies*. CBS only has *copies*, so their "handwriting expert's" opinion is worth absolutely nothing.