A number of bloodstained items have been found in the last two of four punishment cellars.
The Telegraph reports: Deputy Police chief Lenny Harper said that at this stage it was not clear if the items - details of which have not been released - had an innocent explanation.
The discovery comes two days after police found large amounts of lime, which can be used to disintegrate corpses, in a pit uncovered at the former children’s care home.
The skull fragment found buried under the stairwell several weeks ago was also buried in soil containing a large amount of lime. Archaeologists who conducted tests on the skull fragment said the protein collagen had been completely destroyed in the bone because of the lime.