The Scottish Football Association will ask Celtic boss Gordon Strachan to explain the circumstances which led to his dismissal at Pittodrie after receiving the fourth official's report into the rumpus.
Strachan was sent from the touchline by referee Charlie Richmond after arguing with an Aberdeen steward during Celtic's 3-1 Clydesdale Bank Premier League victory on Sunday.
Richmond's report arrived with the SFA yesterday and the receipt of fourth official John Underhill's statement moves the situation forward.
The Celtic manager faces a potential six-match ban over the incident, but it is likely to be some considerable time before any punishment is set out.
The severity of the automatic suspension depends on his success in appealing against a four-match ban from last season.
The former Scotland midfielder is awaiting a hearing into his dismissal by Stuart Dougal for dissent during a 3-1 defeat by Hearts in April.
SFA head of discipline Drew Herbertson said: 'We will write to Gordon Strachan and Celtic in regard to the incident.
'The disciplinary committee met yesterday and agreed a schedule of dates for the season ahead.
'We need to establish whether Gordon Strachan and Stuart Dougal are able to attend the date set out and we will not announce the details before such time.'
Strachan was banned from the touchline for two games after being dismissed by Dougal at Hearts a year ago following a spat with then Tynecastle coach John McGlynn.
The suspensions automatically increase by two matches for each offence over a rolling three-year period.
But Strachan is certain to contest his dismissal at Pittodrie.
The SFA would not reveal what offence Strachan had been dismissed for.
Strachan has also maintained his silence over the affair, but first-team coach Tommy Burns accused the steward of telling 'blatant lies' over a gesture made by assistant boss Garry Pendrey following Celtic's second goal.
Burns claimed former Aberdeen player Strachan was stating to a policeman that the gesture was to mark the scoreline and was not offensive.