A man from Newcastle was cautioned for sending abusive Twitter messages to a Premier League referee.
Mark Halsey made a complaint to police in his home town of Bolton about online posts sent after refereeing Liverpool's home defeat to Manchester United.
Mr Halsey, 51, sent off Liverpool midfielder Jonjo Shelvey in the first half of the match and awarded their opponents a late penalty.
It is understood several of the messages referred in derogatory terms to Mr Halsey having had throat cancer.
Police said a 27-year-old man they interviewed from the Newcastle area admitted being responsible for some of the messages. He was subsequently cautioned.
Officers say they are continuing attempts to trace anyone else responsible for posting the abusive messages.