He called for a more wide-ranging review of Britain's procedures for dealing with missing children, insisting that if Britain had a system such as the "Amber alert" used in the United States or similar systems used in France and Belgium, Shannon could have been found within hours of her disappearance.
British law enforcement does have a system for notifying the public under certain circumstances, but police pointed out that because it is for use "in potential child abductions where a vehicle or partial vehicle details are known," it would have been "wholly inappropriate" to have used it in Shannon's case.
"The suggestion it could have somehow speeded up Shannon's recovery is totally inaccurate," a police statement said.
Police sources defended the amount of time it took to find Shannon just one mile from her home, with a relative.
There were 200 officers on the case and they interviewed members of Shannon's immediate family, and then turned to her extended family, which amounted to hundreds of people, police said.
Police said they had knocked on the suspect's door because they were working their way through that long list of relatives, and not because they had received a tip, as has been reported in some of the British media.
According to Britain's Daily Mail newspaper, one possible factor that took so much police time is that "an astonishing 1,387 registered sex offenders live within a 20-mile radius of the nine-year-old's family home in Dewsbury Moor, West Yorkshire. And with so many suspects within half an hour's drive, police had a huge list to work through."
Perman-Kerr told ABC News that like many other kidnap victims, Shannon may have developed an involuntary attachment to her kidnaper.
"She will wonder what will have happened to the person that captured her, because she may have a feeling of responsibility towards him," Perman-Kerr said. "Often people, particularly children, feel guilt and shame about their part in whatever happens. Very often children will feel that way without telling their parents. Stockholm syndrome can develop in adults, but it's more likely in children."
Police did immediately say when Shannon would be returning return home.