The next morning police officers find Mackay in Stockwell, South London. He is placid and compliant because he is hungover. He had spent all the money from the robbery on alcohol.
He immediately admits to the murder of Father Crean and says a “white mist” had come over him and he’d done it in a fit of anger. On the journey to the police station at Gravesend he takes police to a garage near Clapham where he says he disposed of the knife he had used in the murder.
During police interviews Mackay describes the murder vividly and relives it step-by-step. It is noted that talk of all the blood makes Mackay excited and it jogs his memory of standing for an hour after the murder, watching the body float in the water.
Mackay is charged with the murders and held at Brixton Prison awaiting trial.