Some witnesses dispute an element of William Tyrrell’s foster mother’s recollection of the day the three-year-old went missing, an inquest has been told.

William’s foster mother 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 New South Wales’s mid-north coast, late on the morning of 12 September 2014.

Det Sgt Laura Beacroft, who joined the investigation in September 2015, said she had 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 would have noticed the cars as vehicles were rarely parked on the wide, quiet street, the inquest was told.

Beacroft said the foster father, who previously told the inquest he was out of town for work between 9am and 10.30am, also could not 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, Ronald Chapman, 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.

William Tyrrell was wearing a Spider-Man suit when he went missing in September 2014.

Beacroft told the inquest she did not believe Chapman had made up what he had seen from outside his Laurel Street home the morning of 12 September.

Neither car had 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.

Beacroft said it was possible the two cars Chapman saw just happened to be heading in the same direction and were not in convoy.

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” was not an official term used by NSW police and had no settled definition in policing worldwide, 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 1,140 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.