Murdered schoolboy Daniel Morcombe.

Murdered schoolboy Daniel Morcombe. Photo: Supplied

Passengers on a bus travelling to a Sunshine Coast shopping centre 10 years ago were worried about a little boy left behind on the side of the road.

They would come to learn that the young boy wearing a red T-shirt was Daniel Morcombe, who was dead "almost certainly" an hour later.

Terry Theuerkauf was sitting at the back of a bus travelling to Sunshine Plaza at Maroochydore on the afternoon of Sunday, December 7, 2003, with his sister Fiona and friends Peter Murchie and Abby North.

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 saw a young boy wearing a red T-shirt waiting on Nambour Connection Road, under the Kiel Mountain Road overpass.

"He had a stick in his hand and he was waving at the bus," Mr Theuerkauf told Brisbane's Supreme Court on Tuesday.

"I only took notice, because the boy wanted to get on the bus. He was trying to stop it."

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

The bus did not stop.

Mr Theuerkauf recalled seeing a "sort of scruffy" man standing behind the boy.

"He was standing right back. There was a clay wall ... he was leaning against it," he said.

Police allege that man was Brett Peter Cowan, who is now on trial in the Supreme Court, charged with Daniel's murder.

Earlier that Sunday afternoon, Craig Beattie was driving along Nambour Connection Road, with his baby daughter in the back seat.

He too saw a young boy on the side of the road.

"He was just walking along, looking up at the trees," he said.

Blake Rogers, a neighbour of the Morcombe family, also spotted Daniel walking along the side of the road that day.

Mr Rogers twice saw Daniel on Nambour Connection Road when he drove home from the beach and then when he drove to work about 2pm.

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.