A pensioner has been found guilty of sending a menacing email to a range of legal officials including Sussex Police and Crime Commissioner Katy Bourne.
In his message, John Hoath, 74, accused Sussex Police officials of helping people evade justice, Wimbledon Magistrates' Court heard.
Hoath, of Lewes, East Sussex, also threatened to carry out a citizen's arrest on those he contacted if they did not surrender to him in seven days.
The judge said Hoath could face jail.
His email was sent on 9 July to two Sussex Police solicitors, the forces' Professional Standards Department and the office of the Sussex PCC.
Hoath denied he had intended any malice in his message, but was convicted of sending an electronic message of a menacing character.
'Not a joke'
Ms Bourne gave evidence by video link.
During his summing up district judge Andrew Sweet recounted Ms Bourne's comments, that the email had been "entirely alarming" and had caused her "sleepless nights" as it was "the kind of allegation that loses you your job."
Mr Sweet said he was satisfied the email message "was not a joke" and it was "meant to be taken seriously".
He conditionally bailed Hoath to return to the same court for sentencing on 27 February.
Ms Bourne was elected as the Sussex PCC in November 2012, with the aim of holding the chief constable to account for the performance of the force.