Signs of blood have been found on part of a sandal and on soil inside a toy car recovered by police searching for missing Sheffield toddler Ben Needham.
Ben was 21 months old when he disappeared on the Greek island of Kos in July 1991.
South Yorkshire Police said forensic work was being carried out in Aberdeen to try to extract DNA from the items.
Det Insp Jon Cousins said it was still his "professional belief" Ben died in an accident at the farmhouse.
Details of the findings have been released on the 26th anniversary of Ben's disappearance.
Ben went missing while playing near a farmhouse, which was being renovated by his grandfather in Iraklis.
About 60 items discovered during the search were brought back to the UK for analysis, some of which were sent for testing at the James Hutton Institute in Aberdeen.
Professor Lorna Dawson, head of the soil forensics group, said the team of scientists had discovered the "profile indicative of human blood decomposition on a fragment of a sandal."
The profile had also been found on soil from inside a toy car, however, the stronger signal had been found on the footwear sandal, she said.
Professor Dawson said the discovery was the "chemical finger print" of compounds left behind "when there has been decomposition or decay".
"There's a strong indication from this chemical profile that this was present on those items as a result of blood decomposition," she said.
"It's significant in identifying that 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 that item by extracting the DNA."
Det Insp Cousins said: "Based on the facts and the information obtained, as previously stated it is still my professional belief that Ben died as a result of a tragic incident at the farmhouse involving heavy machinery.
"It's my belief that [the findings] corroborate and strengthen that theory."
The Needham family has been informed and the force would continue to assist the Greek authorities with any ongoing enquiries, South Yorkshire Police said.