Disgraced detective Gary Jubelin has described William Tyrrell's foster mum as a 'very decent human being' as she is named as a person of interest in the missing three-year-old's disappearance.
Jubelin was once the head of the taskforce investigating the case when William vanished from his foster grandmother's home in Kendall, on NSW's mid north coast in 2014.
Speaking to 2GB, the former detective said the new developments in the investigation were 'strange' as police return to the site the little boy was last seen.
'My impression is she (the foster mother) is a very decent human being,' he said.
'I certainly, whenever I'm dealing with victims and this is the detective in me, I'm always looking out for something suspicious and I've got to say I have not picked up any of that.'
William's foster mother has become a person of interest in the case, however, the case has had hundreds of persons of interest.
Disgraced detective Gary Jubelin has described William Tyrrell's foster mum as a 'very decent human being' as she is named as a person of interest in the missing three-year-old's disappearance
Being a person of interest does not necessarily suggest William's mother is a suspect and she has vehemently denied any involvement in his disappearance.
NSW Police Commissioner Mick Fuller earlier unleashed on Jubelin for leaving the investigation 'a mess'.
He admitted on Tuesday the early years of the investigation had wasted time chasing the wrong suspects.
Jubelin led the investigation into the missing toddler's disappearance for five years until he resigned over misconduct allegations.
The ex-homicide detective was convicted of covertly recording four conversations with Paul Savage - who was wrongly singled out as a suspect in the case - and was fined $10,000. He later lost a subsequent appeal.
Commissioner Fuller attacked his former top detective's approach to the case which he said had set back the current renewed search.
'The investigation was looking at some persons of interest that were clearly not, and I think some time was wasted on that, and bushland is overgrown,' Mr Fuller told 2GB.
'But a new team on-board inherited, what was a bit of a mess, and have cleaned up that investigation.'
Mr Jubelin hit back at Mr Fuller's criticism and insisted his bosses had approved of his every move while he was leading the search for William.
'I led the investigation for four years during which time detailed reports were submitted on a monthly basis outlining the direction of the investigation,' he told The
