William Tyrrell's foster mum says she saw two unknown cars in the street just before the boy went missing, but police have been unable to back up that account, an inquest has been told.
The inquest into the three-year-old's suspected abduction heard on Monday the foster mother - who can't be named for legal reasons - told police she saw the sedans parked in the street outside William's foster grandmother's home on the morning he disappeared.
William was last seen at that home, on Benaroon Drive in Kendall on NSW's mid-north coast, late on the morning of September 12, 2014.
Detective Sergeant Laura Beacroft, who joined the investigation in September 2015, said she'd been unable to corroborate the foster mother's statement about the cars seen at 7.30am and 9am.
Under questioning from a lawyer for William's biological father, the detective told the NSW Coroners Court some witnesses were adamant the cars described were not there.
One woman said she was sure she'd have noticed the cars as vehicles were rarely parked on the wide, quiet street, the inquest was told.
Det Sgt Beacroft said the foster father, who previously told the inquest he was out of town for work between 9am and 10.30am, also couldn't remember seeing the vehicles as he left.
William's foster mother called police about 10.56am, telling them her boy was wearing a Spider-Man suit when last seen about 10.30am.
The inquest was told a local resident reported seeing two cars - one with a boy in the back seat wearing a Spider-Man costume - driving away from the area William was last seen.
Det Sgt Beacroft told the inquest she didn't believe Ronald Chapman had made up what he'd seen from outside his Laurel Street home the morning of September 12.
Neither car has been identified during the investigation, the inquest was told.
Laurel Street sits east of a road that connects to Benaroon Drive and west of roads connecting to the Pacific Highway.
Det Sgt Beacroft said it was possible the two cars Mr Chapman saw just happened to be heading in the same direction and weren't in convoy.
Mr Chapman is expected to give evidence at the inquest this week.
While the inquest is sitting in the regional town of Taree this week, police on Monday launched a fresh local search for evidence.
Police, sniffer dogs and SES personnel scoured bushland around Kendall and the nearby township of Herons Creek.
The inquest was also told more than 400 "persons-of-interest packages" were created as police tried to identify and interview every person who could have taken William.
Acknowledging "person of interest" wasn't an official term used by NSW Police and had no settled definition in policing worldwide, Det Sgt Beacroft said there was a very low standard to meet in order to become a person of interest.
Officers spent months interviewing hundreds of the 1140 people living in the town with a list of set questions before making more targeted inquiries with so-called persons of interest.
Residents were asked to list all deliveries and tradespeople their home had received over a one-year period and to document their movements the morning William went missing.
The inquest will resume on Tuesday.
Australian Associated Press