Steve Smith was not aware of key elements of Australia's ball tampering plot until he saw the incident on the Newlands big screen, according to Cricket Australia's investigation.

While David Warner refused on Saturday to divulge his exact involvement in the ball tampering crisis that has rocked Australian cricket, details are starting to emerge from the events of last Saturday at Newlands.

Steve Smith, addresses the media at Sydney Airport on Thursday. Credit:Janie Barrett

Fairfax Media can reveal investigators were told Smith did not know how the plan would be carried out until after Bancroft had been exposed on the big screen. It's believed they found Smith had expressed his dislike of the plan but did not attempt to stop it.

It's understood CA's investigation found that the sandpaper was used twice on the ball, which umpires believed had not been sufficiently altered to warrant replacement, and had come from a kit bag though it's unclear who supplied it for use. Sandpaper is commonly used by players to smooth their bats.