Above suspicion
too highly respected to be suspected of a crime or wrongdoing.
- He was a respected academic and above suspicion.
Under suspicion
considered as possibly guilty of a crime or wrongdoing.
- The police intercepted the traffic on the roads to examine vehicles under suspicion.
On suspicion
(arrest or detain somebody) on the ground of suspicion.
- He has been questioned on suspicion of slandering the Prime Minister.