Fringe | Season 4 | Episode 13 | “A Better Human Being”
The team investigates a series of murders with the help of someone who appears to be telepathically linked to the perpetrators, discovering that (once again) a scientist’s creations have turned on him. Also, Olivia is inexplicably full of Cortexiphan.
I’ve never heard of chromosome imaging being useful in a forensic investigation, but then Walter is nothing if not unorthodox. It would probably have been simpler to perform a DNA profiling technique such as STR to figure out whether the people were related.
If the half-brothers were trying to protect their identity, wouldn’t it have made sense to kill or silence the doctor first? After all, he could have gone to the police or posted his documents on the internet at any time.
Potassium iodide (KI) has a strong, salty, bitter taste and it’s likely that Walter would be able to identify it. However, there’s no reason for it to be present in the fake Cortexiphan solution since it’s colourless and water would look exactly the same.
Red No. 4 food colouring (E125) is a not-very-common red dye. It is highly unlikely that Walter would be able to taste it, given the low concentration and the overwhelming presence of potassium iodide. He might be able to take a guess from the colour of the solution, but given the vast array of reddish food colourings and coloured chemicals it’d be impossible to match the colour to a specific chemical.