Transformation:
1. He didn't know it but his colleagues blamed the accident on him.
=> Unbeknownst........................................................... accountable for the accident.
2. Rio succeeds in making a serious point while at the same time being hysterically funny.
=> Not............................................ stiches.
3. They tried but didn't succeed in redeeming their sins.
=> In............................................. for their sins.
4. The assistants on e-mail; otherwise they'd never have received the news when expected.
=> The assistants,......................................... dot.
5. No matter what they did, they weren't able to explain why she disappeared.
=> Try.................................. in mystery.