The investigation into the disappearance of West Auckland toddler Aisling Symes now includes interviewing known child sex offenders and profiling "suspicious people", the officer in charge of the inquiry says.
Aisling was last seen walking near her home in Longburn Rd, Henderson about 5.30pm on Monday.
Police say there is no evidence she has been abducted but they are treating it as more and more likely after searches for her have turned up nothing.
Inspector Gary Davey told Campbell Live police had been investigating the possibility of an abduction from the beginning of their inquiry, and had serious concerns for her safety.
"As time goes on and there's been no more sightings of Aisling, that investigation phase has taken more prominence, to the point where we have already begun interviewing, profiling suspicious people, people that have been convicted of these types of offences or have propensities for these types of offences."
Police were also looking at recently reported suspicious behaviour in the area to identify possible abduction suspects.
"There have been some reports of suspicious activity but I'm not prepared at this stage to say that it is linked or could possibly be linked, but we'll be looking through all those."
Mr Davey said police were "absolutely confident" they would have found Aisling if she'd fallen into water behind her home.
It was likely that the longer she had walked for, the more she would have been noticed by passing people and traffic.
Mr Davey said police were still keen to speak to an Asian woman seen talking to Aisling just before her disappearance about 5.30pm on Monday.
He was surprised that woman had not contacted police, and they were looking to identify her and interview her about what had taken place.
The woman was in her 30s, about 165cm tall with a medium build and long straight black hair.
She was wearing a black crew neck top, with three-quarter length sleeves, three-quarter length blue jeans, black leather sandals and black socks, and had a black and grey medium sized dog on a lead.
Aisling was described as being tall for her age, of European appearance, with light brown hair.
She was believed to be wearing a green parka jacket or ski jacket, blue jeans embroidered with flowers, and white tennis shoes.