Cardiff City have submitted a dossier regarding the conduct of former manager Malky Mackay and former head of recruitment Iain Moody to the Football Association, the governing body has confirmed.
An FA spokesman said: "The FA can confirm it is currently investigating this matter."
Cardiff sent the dossier to the FA detailing a number of issues related to Mackay and Moody's time at the club.
The Daily Mail has reported that the document contains allegations of racist, sexist and anti-gay text messages.
On Wednesday, a source told ESPN FC that Mackay will not be appointed as the new Crystal Palace manager after initially being identified as the club's preferred candidate.
Palace announced on Thursday that Moody had quit his role at Selhurst Park over the matter.
"In light of the events of yesterday, sporting director Iain Moody has tendered his resignation and it has been accepted with immediate effect," a club statement read. "There will be no further comment from the club on this matter."
Cardiff owner Vincent Tan sacked Mackay in December 2013, just a few months after the Scot had ended the Bluebirds' 51-year wait for a return to top-flight football.
Two months earlier Moody, Cardiff's former head of recruitment and now Palace director of football, had been placed on gardening leave before being subsequently dismissed.
Mackay launched a 7.5 million-pound legal claim against Tan for compensation and wrongful dismissal after his sacking but dropped the claim in May and issued an apology to the Malaysian businessman.
Cardiff have declined to make any public comment on the dossier and the matter is now in the hands of the FA.
Earlier this week, Palace were fined by the Premier League for their part in the "spygate" saga involving Cardiff last April.
The Premier League determined that Palace had breached its "good faith" rule -- B16 -- by obtaining information about Cardiff's team ahead of their 3-0 win when the two clubs were relegation rivals.
The Welsh club had complained to the Premier League that Moody had contacted Cardiff employees for information in the build-up to the game, an accusation Moody denied.