What other people? In regard to his arrival at WHF, Ps Bews and Pc Myall used identical wording to state that he did not appear dishevelled in any way and did not appear to be emotionally excited.
I can not comprehend how he could have thought it was a good plan to stand next to the police outside the house when he would have had no idea how he would have reacted to killing 5 people. The phone call was obviously not an alibi as it could not be proved. He had no idea how much blood or GRS would have been on him or how much he would have had to clean up.
Unless the police were totally stupid then it would have been obvious he was a man who had just killed 5 people , rushed to get rid of all the evidence and cleaned himself up. Let alone the fact that he would have been totally panicking about the fact he had to shoot Sheila twice.
His reactions were totally in line with someone who thought he was possibly going to a scenario that was going to be tricky to sort out - but as the night unfolded and he was begging the police to go in and save his family the realisation of the situation began to sink in.