"This Test match needs to proceed, and in the interim we will continue to investigate this matter with the urgency that it demands," CA chief executive James Sutherland said.
Smith travelled to the ground on the team bus on Sunday then sequestered himself from the team.
Smith's 10 ashen-faced teammates all went through their standard pre-play routines on the morning of day four but their leader was nowhere to be seen.
The gifted batsman is likely to be charged by the International Cricket Council but the prospect of more stern punishments loom large.
"I won't be considering stepping down. I still think I'm the right person for the job," Smith told reporters after day three.
The ugly episode has prompted an outpouring of shock and condemnation, with the Australian Sports Commission leading calls for Smith and "any other members of the team leadership group or coaching staff who had prior awareness" to be stood down.
