“A Man Alone” is episode four of season one of Star Trek: Deep Space Nine.
A Bajoran criminal who Odo had previously put away for murder turns up on the station, having being released by the provisional government. Odo has a confrontation with him, and then the man turns up dead.
As Odo points out, all the evidence points to himself being the only one capable of carrying out the murder. Given Odo’s history – he also worked for the Cardassians – feelings are quickly stirred up against him on the station, and a howling mob demands that he be punished.
Odo has to be taken off the murder investigation, as having a suspect investigating a murder is rarely a good idea, but what actually happened needs to be found out quickly.