Stephen Waterson has admitted crushing three-year-old Alfie Lamb with his car seat.
Waterson, 26, crushed Alfie in the footwell of his Audi convertible while his mother Adrian Hoare, 23, looked on.
Detective Chief Inspector Simon Harding, of Scotland Yard, said there had never been a case like it where a child was crushed by an electric car seat.
– How did Alfie die?
Alfie died in hospital three days after suffering irreversible injuries consistent with crush asphyxiation.
– How could a car seat cause those injuries?
The Audi convertible’s front passenger car seat operated by the touch of a button. It left a space of between 30cm and 9.5cm in the footwell behind where Alfie sat. The powerful mechanism would stop when it met resistance but not automatically move forward.
A senior forensic collision investigator found that at peak, it applied between 78kg and 81kg of pressure, and averaged 63-67kg. The seat took 13 seconds to move back fully.
– How long would it have taken for Alfie to be fatally crushed?
A matter of minutes, said Mr Harding. Waterson maintained he only moved the seat back once, although others in the car disputed this.
– How did Alfie’s mother and her boyfriend react?
Waterson fled the scene before medics arrived, sold his car days later and threatened witnesses in the case.
Meanwhile, Hoare immediately set about fabricating false stories for authorities to protect him.
Mr Harding said: “Stephen Waterson and Adrian Hoare, even after Alfie died, were more concerned about being together. Stephen Waterson was concerned the real story never came out. He went on to intimidate and assault people.”
– What kind of challenges did the investigation present?
An initial post-mortem examination proved inconclusive and the defendants were not arrested until February 28 last year as police grappled with false accounts.
Mr Harding said police faced “continual lies” from the moment Alfie was found at the side of the road.
“They made up stories of how they got there, how Alfie died, gave false names of people, false cars, false locations and officers had to follow that through. There was no CCTV so it took a while for us to understand the story.
“London Ambulance Service were immediately suspicious after a medic overheard Hoare say she could not say what happened and her sister eventually came forward to reveal what she was told.”
– What about social services?
Social services had been involved in Alfie’s care as well as that of other children connected to the case.
The Medway Safeguarding Children Board conducted a serious case review into agencies’ dealings with Alfie.