He reminded jurors the child was noted as having dry hair, was wearing a nappy, the bath tub was empty of water and no water was found in his lungs.
And he recalled how witness Janet Gee, a work colleague of Varley, told the court how Varley had told her of his “dark thoughts” about drowning or suffocating the child.
Concluding his closing speech, the prosecutor added: “Preston was at the mercy of Jamie Varley on the 27th of July, and paid for it with his life.”
Varley denies murder, manslaughter, two counts of assault by penetration, five counts of cruelty to a child, grievous bodily harm, sexual assault of a child, 13 counts of taking indecent photos or videos of a child, one of distributing an indecent photo of a child, to his co-accused, and one of making an indecent photo.
McGowan-Fazakerley denies allowing the death of a child, three counts of child cruelty and one count of the sexual assault of a child.
The trial continues.