Why is Roselyn Sanchez even on Without a Trace?

Roselyn Sanchez is a very lovely woman who is incapable of speaking a single word clearly in English or Spanish. What she does not mumble, she mispronounces. Her problem is not her accent; her problem is the salami that is stuck in her larynx. She needs speech therapy. After she becomes verbal, everyone will be able to make some kind of judgment about whether she can act. Right now, her only option is to strap a bicycle horn around her neck and try for the Harpo Marx role.

I didn't understand it either except to add another female role to the cast. Cold Case seemed to have a similier character (making me think it was a network decision) but they wrote her out.

Yep, this piece of eye candy doesn't hurt one bit.

What's wrong with eye candy?

I have wondered the exact same thing. She doesn't seem to fit other than to give Jack a hard time about his ties.