Maurice Chambers and Zoheb Sharif have each reported incidents of racism while at Chelmsford, while John Faragher has resigned as chair following an incident during a 2017 board meeting
Katharine Newton QC will be part of the independent investigation into historic allegations of racism at Essex.
She has more than 20 years in employment law and regularly appears in the employment tribunal, High Court and the appellate courts, including the Court of Appeal and the Supreme Court.
In 2016 and 2017, Ms Newton led the investigation into accusations of bullying and racism against former England women's football manager Mark Sampson.
A club statement read: "The appointment of such an eminent legal figure underscores the Club’s determination that all allegations, regardless of when they took place, will be investigated thoroughly and independently."
The examination of previous behaviour will come in the wake of a succession of allegations to emerge from Essex in recent days.
Two former players Maurice Chambers and Zoheb Sharif both claim to have suffered incidents of racism during spells at Essex.
In addition, John Faragher has stood down as chair after the use of racist language during a board meeting in 2017 came to light. Faragher denies the accusation.
The England and Wales Cricket Board have also pledged to investigate both the incidents and the club's handling of their own inquiries.
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