As police teams methodically searched the area, Dawson’s team were using science to narrow the hunt.
She said: “We used gas chromatography (the process whereby the various elements of a compound are separated into their distinct parts for individual analysis) in the evidential phase of the operation and showed the peat on the soles of the Timberland boots also had the same organic profile as was found at the scene.
“Our botanist identified the individual recovered mosses. From this we knew that the person who wore the boots had likely stood in the area where Emma was found. There was also an organic peat stain on the boots which showed they had been partially submerged in peaty water.
“Puddles containing peaty water were located in the hollows between the clumps of moss and rushes at the scene. Trees had been planted around 2016 in that general area and may not have been felled for another 40 to 60 years, which might have left Emma hidden in the undergrowth.
“She was covered with clumps of mosses and the rushes which had been pulled from the ground a few metres away from her body in an attempt to conceal her.
“Soil can be distinctive in a range of chemical, physical and biological characteristics, including the soil organic profile, soil elemental composition and soil mineralogy. Depending on the type of soil, different methods are used in forensic case work. In this case, because of the organic nature of the soil, organic plant wax marker analysis was used. In addition, the distinctive plant community added another link to the scene.”
Without the police and forensic experts’ efforts Emma’s body may never have been found and her family would not have known if she was alive or dead. Dawson added: “What the police search did was to return Emma to her family and give them that at least. It would be hugely painful for them to be left without that knowledge.”
https://www.sundaypost.com/fp/emma-faulds-murder-soil-forensic/
For information
That is an example of direct forensic evidence as is the murderer's DNA found under the driver's seat of Emma's car.
Both examples of direct evidence which helped to nail a killer.
I think you may not totally understand the meaning of direct evidence and circumstantial evidence.
Direct evidence is evidence that proves a fact with no inference needed to apply to the evidence
The most common form of direct evidence is an eyewitness account of the actual crime taking place
Circumstantial evidence is evidence that relies on inference to prove a fact.
Forensic evidence can still be circumstantial, such as a fingerprint in a car.
“Circumstantial evidence is evidence that relies on an inference to connect it to a conclusion of fact—such as a fingerprint at the scene of a crime.”https://en.wikipedia.org/wiki/Circumstantial_evidencehttps://en.wikipedia.org/wiki/Direct_evidenceWith that being said, the other 2 cases you mention, Pillay and Fleming, was there any direct evidence or even forensic evidence in those cases?