Premier Colin Barnett has revealed the Department of Premier and Cabinet has "interviewed" key staff in his office over the Troy Buswell affair.
Mr Buswell remains on personal leave after a breakdown that occurred shortly after he crashed his ministerial car after hours of drinking at a Kings Park wedding.
WA Police are continuing their investigation into the traffic matter but Mr Barnett said yesterday that he did not know if they had spoken to Mr Buswell yet.
They spoke to Mr Buswell's chief of staff Rachael Turnseck last week. It is understood she had some knowledge of the damage to his car but she did not tell Mr Barnett or his staff about it until media inquiries two weeks after the incident.
"The Department of Premier and Cabinet has interviewed staff in my office," Mr Barnett said yesterday.
Those interviewed are understood to be his chief of staff Brian Pontifex and his senior adviser Narelle Cant, who met for 45 minutes with Ms Turnseck on February 25, two days after Mr Buswell's breakdown. "My understanding is that the health of Troy Buswell is improving but it will still take some time for him to be able to return to work," Mr Barnett said.