What blood? Nothing was forensically identified as being blood in that apartment, as far as I'm aware.
I've never even found a mention of DNA on the bedroom wall.
I'm really not sure about that. For instance, there was definitely something on the key card from which Gerry's dna was extracted, but it wasn't specifically identified as blood.
If not blood, then what?
Or is it simply that in the report, they don't trouble to say what the body fluid is from which a result has been extracted, even though they do know it's blood?
After all, what's important is, not the material from which a dna result has been extracted, but the result itself.
ETA: Lowe does say that it is not possible to identify the material from which results are extracted by
low copy number DNA.
And I reckon Grime takes that a stage further in saying Keela, in particular, will detect blood even when they can't find a trace in the laboratory.
I don't think that (statement of Grime's) is true ...