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Police hid before arresting Cowan

Detectives hid behind sheds and machinery before arresting Brett Cowan in the Glasshouse Mountains and charging him with the murder of Daniel Morcombe.

PT1M41S http://www.canberratimes.com.au/action/externalEmbeddedPlayer?id=d-32pvj 620 349

Daniel Morcombe's remains would have been covered twice by floods before they were discovered in an old sand-mining pit in the Sunshine Coast hinterland, a court has heard.

Griffith University Professor Jonathon Olley, who specialises in water science, testified at the trial of Daniel's accused murderer Brett Peter Cowan in the Supreme Court in Brisbane on Thursday.

Professor Olley told the court the property known as Lot 1 on Kings Road, Glass House Mountains, where Daniel's remains were found, would have been flooded on May 21, 2009 and again on January 21, 2011.

Murdered schoolboy Daniel Morcombe.

Murdered schoolboy Daniel Morcombe. Photo: Supplied

It is alleged Mr Cowan dumped Daniel's body at the base of an embankment near the sand mining pit and dragged it towards Coochin Creek on December 7, 2003.

The court previously heard Mr Cowan stripped off Daniel's clothes and threw them in the creek, before covering the schoolboy's body with leaves and branches.

Professor Olley visited the sand mining site on four occasions and determined a layer of sediment, up to a metre deep, had been deposited across the site during the floods.

Brett Peter Cowan listens to evidence in Brisbane's Supreme Court.

Brett Peter Cowan listens to evidence in Brisbane's Supreme Court. Photo: Nine News

He advised police to excavate the site to the level it would have been before the floods - five hundred cubic metres of sand was eventually removed from the pit.

Once the excavation was complete, Professor Olley said he identified three "depressions" or "flow paths" across the site.

"Significantly, there were finds [remains] found along each of those flow paths," he told the court.

Denise and Bruce Morcombe talk to the media, thanking the public for their support, on Monday, August 15, 2011, two days after a man was charged with the murder of their son Daniel. They are outside the Daniel Morcombe Foundation headquarters on the Sunshine Coast. Click for more photos

Search for Daniel Morcombe's remains

Denise and Bruce Morcombe talk to the media, thanking the public for their support, on Monday, August 15, 2011, two days after a man was charged with the murder of their son Daniel. They are outside the Daniel Morcombe Foundation headquarters on the Sunshine Coast. Photo: Michelle Smith

However, Professor Olley said it would have been unlikely that material thrown into Coochin Creek would have travelled any farther than 300 metres downstream.

"To describe Coochin Creek for you it is very windy, it has a large amount of fallen trees in it and a lot of roots encroaching on the channels," he told the jury.

"You have to picture something that's very heavily vegetated."

Professor Olley said any material thrown into the creek would have been "hooked up in that vegetation relatively quickly".

The court previously heard that police divers found three items of clothing in the creek - a pair of Rip Curl shorts, a belt and the elastic band of a pair of Bonds underwear - believed to have belonged to Daniel.

All three items were found among the tangled roots and branches in the creek, the court heard.

Mr Cowan is charged with one count each of murder, indecently dealing with a child under the age of 16 and improperly dealing with a corpse.

He has pleaded not guilty to all charges.

The trial continues.