Human tissue found on a toy car and sandal believed to have belonged to Ben Needham could help solve the mystery of what happened to him.
The 21-month-old toddler went missing on the Greek island of Kos 26 years ago to the day.
He was with his grandparents Eddie and Christine at a remote farmhouse Eddie was helping renovate when he simply vanished.
South Yorkshire Police said they believed Ben died as a result of an accident involving a digger on July 24 1991.
Detective Inspector Jon Cousins said the new findings "corroborated and strengthens" this theory.
Blood found on the items will now be DNA tested.
The sandal was reportedly found in 2012 at the site where Konstantinos "Dino" Barkas was operating a digger, while the toy car was discovered last year at another spot.
Mr Barkas is believed to have died from stomach cancer in 2015.
Despite extensive searches of two sites Ben's body has never been found.
His mother Kerry Needham begged for anyone with information to come forward.
"This confirms everything the police have suspected. It makes it all a little too real. We believe what they believe," she told the Daily Mirror.
She added: "It shows more of a conspiracy because they didn't find Ben's body.
"That proves it to me without doubt they obviously moved him and buried him and for whatever reason dug him up.
"There's no other explanation. It's all been a massive cover-up."
Professor Lorna Dawson - one of the world's leading scientists in her field - said the findings could provide evidence of Ben's death.
"It's significant in identifying there had been a human who had bled in contact with those items.
"The biologist has to come in now and identify who left that blood on the item by extracting DNA."
Click below to hear Ben's mother Kerry's reaction:
Ben's sister Leighanna also appealed for information about her brother.
"They are putting an entire family's suffering on hold, yet again , when this could have been over and done with 25 years ago.
"But we're always hopeful that someone will come forward and brave the stigma that has been attached to them, from keeping it from us."
Mark Witty reports: