Former Gillingham player Mark McCammon reported a racist and threatening message to the Metropolitan Police last month and has posted an appeal on Twitter asking his followers to help him find the perpetrator.
McCammon, 34, posted a copy of the Facebook message which used derogatory and racist language and said the player would have his "throat cut" if he returned to the football club.
Last year, the striker was awarded £66,728 at a remedy hearing in a landmark legal victory following a four-day case which heard he had been put "through hell" at Gillingham as he was treated differently from white players.
Gillingham Football Club said that McCammon is the first of "many thousands of staff of various race, religion and creed" to have ever considered a claim on the grounds of discrimination.
Mark McCammon said he was ordered to come into the ground amid "treacherous", snowy driving conditions while some white players were told they were not required.
He also said the club tried to "frustrate him out" by refusing to pay private medical bills to help him regain his fitness following injury.
Instead, he claims he was offered the same operation on the NHS rather than privately, a move he described as "completely out of character" for a Football League club, and that he was fined two weeks' wages when he paid a visit to a private consultant.
In contrast, the former Charlton, Swindon, Millwall and Brighton player said, a white team-mate was flown to Dubai for treatment by an eminent physiotherapist at the club's expense.
Mark McCammon, 33, was unfairly dismissed by Gillingham Football Club after suffering racial victimisation, a tribunal has ruled.
The player had alleged that he and other black players were discriminated against by the club.
Responding to the Ashford Employment Tribunal's ruling, Gillingham FC said the club is "hugely disappointed, in fact staggered, by this decision."
It went on: "As an organisation we are an equal opportunity employer and do not discriminate against, nor victimise our staff."