Mark Clattenburg is facing the prospect of a police and Football Association investigation into allegations he used "inappropriate language" towards Chelsea stars John Obi Mikel and Juan Mata.
Clattenburg was accused by the European champions of making offensive comments on Sunday, which are understood to have been interpreted as racist, during their acrimonious Barclays Premier League defeat to Manchester United.
Chelsea lodged a formal complaint with the match delegate, sparking an almost inevitable chain of events that this afternoon saw the FA announce an investigation and Clattenburg stood down from officiating for a week.
What was far from inevitable, however, was the involvement of the police, who became embroiled in a second high-profile football race case on Monday night after the Society of Black Lawyers demanded they look into whether a criminal offence had been committed.
The police confirmed on Monday night they had received the letter but it is understood it was by no means certain an investigation would follow.
It was unclear whether Mikel, Mata or Chelsea would welcome police involvement, though they themselves had made no complaint as of Monday.
It would also pile the pressure on the FA, who will be desperate to avoid another lengthy disciplinary matter after shelving their own investigation into Terry while he faced criminal charges.
Clattenburg, Michael McDonough, Simon Long and Michael Jones all wore microphones and earpieces on Sunday, although their conversations were not recorded.
Former Premier League referee Graham Poll told BBC Radio Five Live: "A referee's microphone is on open. Everything he says is heard by two assistants.
"So if Mark said something, the assistants would have heard it.
"If a comment of a racial nature was made, I think it should be reported and I think assistant referees will report it because there's no place for it."
Technology could yet be used as evidence, though, if video or audio footage emerges in support of either Clattenburg or his accusers.
August 6 2008 Clattenburg was suspended pending a probe into his business affairs following allegations he owed £60,000 as a result of a failed venture. He pulled out of the FA Community Shield clash between Manchester United and Portsmouth as a result and later sacked by the Professional Game Match Officials board.
February 2009 he was einstated as a Select Group Referee on appeal, but suspended for eight months from August 6, 2008, for "issues relating to his private business affairs".