The actual lines in the drama didn't include "no forensics".
Cook: "But there's still the silencer, the evidence of human blood in it."
Another officer: "Well, no, we can't conclusively prove it was Sheila's blood, and the defence will say it's contaminated."
Stan Jones: "The trial will turn on witness testimony. That's what the jury will remember. That will be what gets them over the line."
Ainsley: "Jeremy can be very convincing, as you found."
Stan Jones: "It will come down to Julie Mugford. That's what will turn it - her word against his."