Speaking on ABC's Good Morning America, the heart consultant said: "We were dining 50 yards away and we could see the apartment from where we were. It's like we were sat in our back garden, all be it at the end of our garden.
"The kids were sound asleep and they were being checked regularly. We didn't think we needed a babysitter. "We are good parents and what we did felt perfectly reasonable at the time. Hindsight is an incredible thing. Clearly we couldn't have predicted what was to happen."
He was also quizzed about the possibility he and GP Kate, also 39, could be prosecuted for leaving Madeleine and two year old twins Sean and Amelie alone in the apartment that night.
He told CNN: "We have been assured by the authorities that what we did fell well within the boundaries of good parenting.
"Madeleine was targeted by a predator and we shouldn't have to be worrying about people getting into our homes and gardens and playgrounds. That is the real criminal act here."
Gerry yesterday (Tue) visited the White House to meet with senior staff of First Lady Laura Bush. Mrs Bush has taken a personal interest in Madeleine's case but was unable to meet Gerry because of prior commitments.