The police team investigating the disappearance of Sheffield toddler Ben Needham is optimistic that excavation work will provide answers.
Digging is now underway on the Greek island of Kos, with two sites to be excavated following a tip-off that Ben may have been accidentally buried there.
Ben was 21 months old when he vanished from outside a farmhouse his grandfather was renovating in July 1991.
The excavation work was planned following a tip-off that Ben may have been accidentally buried by a digger clearing a building plot close to where the youngster was last seen playing.
Material from the plot was moved to two sites on the island, which have now been cordoned off by South Yorkshire Police.
Senior investigating officer, Detective Inspector Jon Cousins, from South Yorkshire Police, said he is 'optimistic' the excavation work will provide answers.
He said the 19-strong search team expects to find 'hundreds' of bones during the dig, all of which will be analysed in laboratories once they are recovered.
But he refused to rule out that Ben may still be alive.
DI Cousins said: "I am continuously keeping an open mind - and still do - as to what happened to Ben in 1991.
"There are still some other live lines of inquiry of what might have happened to Ben.
"All of this has resulted in a lot of myth and legend that has gathered over 25 years as to what has happened to Ben. It has allowed us to pare back and find out the truth and fact. That is why we're here today.
"There are many lines of inquiry. I am keeping an open mind, but what I know at the moment with all the information we have, I've made the decision that it is necessary to do the work that we are going to be doing over the next week or so."
Asked if he expected to find answers, DI Cousins said: "I am optimistic about the search taking place."
He added: "Based on what we found out in 2012 when a search was done nearby, we will be finding many hundreds of bones, each of which will have to be carefully looked at.
"Work will continue tirelessly once work has been assessed."