The character was "killed off" in Season 3 but is back now in Season 4.

I actually have a few questions:

1. Why did Sarah Callies (Dr. Sara) originally leave Prison Break?

2. Did the writers really intend to have her character killed off and brought back; or did they write her out to be gone for good?

3. How/Why did she come back to the show despite being killed off?

#1. Not a 100% sure, but I believe she may have a had a baby & wanted to stay home with it. It seems like I remember reading that somewhere.

#2. & #3. No idea, maybe someone else knows.