One group recently attacked several stallholders at an open-air market in Rafina, a port near Athens, after posing as plain-clothes police checking their permits.
The BBC's Owen Bennett-Jones says the trouble began when one of Mr Sharif's co-accused claimed that there were plain-clothes intelligence officers in the courtroom on Wednesday.
She had no time for semantics: whether to include deaths outside the city walls, whether the plain-clothes soldiers had been billeted with civilians, and so on.
On February 4th Mr Diallo, a young Guinean with no criminal record, was challenged outside his apartment building by four plain-clothes police officers, looking for a rape suspect.