The father of missing Madeleine McCann has had a "productive and interesting" meeting with the US attorney general on the issue of tackling child abduction.
Madeleine disappeared while her parents were at a restaurant
As well as meeting Alberto Gonzales in Washington, Gerry McCann learned about the National and International Centres for Missing and Exploited Children.
Mr McCann is on a four-day visit to the US to find out about US efforts to reduce child abductions.
Four-year-old Madeleine, of Rothley, Leics, disappeared in Portugal in May.
Her family were staying at an apartment in Praia da Luz, Algarve, when she vanished on 3 May.
'Lot of goodwill'
McCann family campaigner Justine McGuinness said: "We're here to find out exactly what happens in America, because we believe the systems in the States are more advanced than systems in Europe."
The American centres were set up in 1984 and 1998 respectively, following the murder of six-year-old Adam Walsh who was abducted from a department store in Florida in 1981.
Mr McCann said: "Obviously my focus just now is on trying to get our daughter back. That's the key thing.
"But I think there is a lot of goodwill out there at the minute, that we might be able to leave something tangible for all children, and I think most people agree that these sorts of crimes should not happen and the perpetrators have to be pursued wherever these crimes are performed."
He added: "[Madeleine] knows very much that we love her and we won't stop searching for her."
On Tuesday, Mr McCann will meet US senators, congressmen and a senior member of First Lady Laura Bush's staff.
Mr McCann's wife Kate remains in Portugal with the couple's two-year-old twins, Sean and Amelie.
The Adam Walsh case led to new legislation passed last year - the Adam Walsh Child Protection and Safety Act.
It strengthened the US's nationwide sex offender registration system and introduced harsher penalties for child sex offenders.