http://www.qt.com.au/news/police-find-suspected-drag-marks-near-creek/1366933/
"A large contingent of SES volunteers and police set up camp at the scout grounds on Tuesday, scouring a massive area of bushland adjoining Kholo Creek, where the body was found, as well as Little Ugly Creek and Flaggy Creek.
Police identified what could have been drag marks near a dirt track leading into one of the creeks. They also found a mobile phone SIM card, but it was yet to be determined if either of the finds had any relevance to Mrs Baden-Clay's death."
Some very good theories point to Allison's body reaching it's position under the bridge by being slid from the bridge itself.
If he/they decided that there would have been a real risk of another vehicle arriving at the bridge .... even while trying to be as quick as possible in their actions, they may have driven to where the Police found "drag marks near a dirt track leading into one of the creeks".
Maybe from there, it was still possible for the activity to be heard by that witness who gave evidence at the Committal.
JMO Although he SIM card was later found to be not connected, this finding of drag marks may have been retained as some evidence.
Another interesting snippet from the same article:
"Meanwhile, Mrs Baden-Clay's husband, Gerard, has enlisted the services of a solicitor and barrister.
Although police refused to comment on whether Mr Baden-Clay was a suspect in the homicide,
it was understood the real estate agent had sought advice on how to deal with police and the media."