Partick Thistle have suspended Jordan McMillan "pending the outcome of an internal investigation".
The 26-year-old full-back has made 13 appearances for the Premiership club this season, having moved to Firhill from Dunfermline in March 2013.
McMillan last featured in the 4-0 win at Inverness CT on 13 December.
The Glasgow club cited "personal reasons" for his omission from the 1-1 draw at home to Dundee on the following weekend.
A brief statement read: "Partick Thistle Football Club has suspended Jordan McMillan, on full pay, pending the outcome of an internal investigation.
"The club, including all of its representatives and employees, will be making no further comment at this time."