Jack Mitchell died, aged 15 in 2016 and a forensic post-mortem examination found he had died from pulmonary infection and pneumonia as a result of injuries sustained as a baby in Laindon.
His biological father, John Doak, was later charged with the murder.
The 37 year-old, of Delgate Avenue, Spalding admitted manslaughter at Chelmsford Crown Court today (Friday 6 November).
He’s due to be sentenced at the same court on Monday 9 November.
Senior investigating officer, Detective Chief Inspector Stuart Truss, said: “This is a truly tragic case of a young man whose future was taken away from him by the injuries sustained at the hands of his father.
“My thoughts also go out to Jack’s adoptive parents who had given him many wonderful years before his death. They continue to live with the sad loss of Jack.”
