I'm assuming they think Summer pushed him off the scaffolding after a bloody fight that caused her brooch to come off. That would make more sense than them believing someone of her stature could hit Theo hard enough to kill him and get blood all over the floor.This is such a basic question I know but how did Theo die? Was he hit over the head in the yard or pushed from a window? I must've missed it.
If the former why would Summer go upstairs to the flat after - thus leaving behind her bloody brooch? And have they said what the murder weapon was? Was it an iron bar? Have they found it? If they're taking George's evidence of her leaving Todd's flat as truthful the weapon must still be in the vicinity.
It's so irritating Swaine hasn't seemed to look into the logistics of the murder at all - just looked at suspects with little to no hard evidence.
(I've watched too many Columbos)
They haven't shown how he died AFAIK!
The writers are deliberately lobotomising Swain otherwise a halfway competent police officer would pull the "Summer did it" theory apart in minutes.