Cook says he kept an open mind when going about his duties at WHF:
Correct Rob, he was leading the Soco investigation, he did keep an open mind, it was very much open to TAFF'S call Murder/suicide, he left WHF at 1.15pm the day of the murders and never returned that day.
He only returned to the murder scene, 4.30pm the next day on the 8th, he went back for the meeting with SJ and Taff at WHF, or he wouldn't have gone back that day either.
SO yes, your right, he was very open, he was open to it being Murder Suicide and nothing else because he was following TAFF'S instructions. Cooke was working under the DIRECTIVE of the senior officer, and in this case it was DCI Jones who had directed to Cook it was a murder suicide at 9.30am that very morning.
I'm trying to back Bamber here, the scene wasn't investigated properly like a crime scene of this Magnitude required, TAFF the senior crime investigation officer leading such investigation, he spent 30 mins at the crime scene on the very first day on a Quick Walkabout, he only went back the next day for a meeting on the 8th and he only went back the day after on the 9th late that evening to Hand the Key's over to the relatives and show Anne around WHF with Stan.
He never looked at the crime scene objectively, it was impossible to Draw such conclusions so early with a 25 minute walkaround that it was murder/suicide, doesn't matter who told him it was murder/suicide, it's not his job to say such until all inquiries are carried out, and a thorough investigation had taken place. He never listened to other officers concerns he never called in the experts, and if he had done his job correctly, Who Knows, Bamber might not even have gone to trial.