The REAL reason, as previously stated, was because the actress who plays Sara had a baby that tahun and wanted to take a break from filming to be with her.
After a break from filming the actress was fine with coming back to the show, so the writers found a clever way to make it appear as though Sara was taken and faked a murder.
sara was not on the third season because she was taken oleh Gretchen and was supposed to be dead. then she cam back in the 4th season because lic found out that they were messing with his mind.
because gretchin put her head in a box so it looked like she was dead because if michael know she escaped she thought he wouldnt brake james out of sona, but the real reason was because sarah wayne callies was pregnant lol
She is pregnant in real life watch Season 2 Episode 22 the part where he meet the brothers at the perahu when Michael hugged her anda can see her baby bump that is why they had to improvise with Season 3 because she can't film also permanently killing her will cause an outcry from fans.