Sebastian Kalinowski, 15, died in a Huddersfield hospital in August 2021.
Prosecutors claim his mother, Agnieszka Kalinowska, 35, and her partner, Andrzej Latoszewski, 36, abused him before his death.
Both deny murder, though Mr. Latoszewski has admitted manslaughter.
Both entered a guilty plea to a charge of child cruelty on Thursday, having previously denied the charge.
Sebastian was taken to Huddersfield Royal Infirmary on 13 August after being found unconscious at his home, according to the court.
Despite the efforts of ambulance crews and hospital staff, he died before midday.
Giving evidence, trainee nurse Sophie Sykes stated that Mr Latoszewski appeared “upset,” but she also observed him “laughing and smirking” while telling hospital staff stories about Sebastian.
She described his behaviour as “a little inappropriate.”
She told jurors that Mr Latoszewski had described Sebastian as a “good child” whose worst punishment had been a “smacked” backside.
During CPR attempts, Dr. Julian Garside noticed “multiple areas of bruising” on Sebastian’s body, including his forehead, jaw, chest, abdomen, and limbs.
According to the court, doctors discovered additional bruising on his body, which raised “significant concern.
West Yorkshire Police Det Insp Oliver Coates told the jury that when he questioned Mr Latoszewski about it, he said Sebastian had “problems with him fighting and falling out of a tree.
Prosecutors claim Mr Latoszewski and Ms Kalinowska subjected Sebastian to a series of escalating “punishments,” including being hit with a piece of wood and whipped with a cable.
According to a family friend who testified on Thursday, Mr Latoszewski told her Ms Kalinowska was “too soft” on Sebastian.
The witness, on the other hand, said she thought Sebastian’s punishments for apparent truancy and lying, which included being barred from family trips, were “too severe.”
The trial is still ongoing.
