Alan Bird, of Common Road, Batley, is facing a life sentence after a jury found him guilty of murdering son Lewis Turner after a trial at Leeds Crown Court.
Bird inflicted life-changing injuries upon Lewis in an attack in 2001 when he was just two years old.
He has already served an eight-year prison sentence over the attack after he pleaded guilty to inflicting grievous bodily harm with intent over the assault which left Lewis with “permanent and irreparable” brain damage.
The 48-year-old was re-arrested and put on trial for murder following Lewis’ death in July 2019.
He pleaded not guilty to murder but the jury reached a unanimous guilty verdict on Tuesday.
Bird was remanded in custody after the trial and will be sentenced on Monday, March 28.
Jurors heard how Lewis developed a “myriad of conditions” which included cerebral palsy as a result of Bird’s attack.
His speech, hearing and sight were impaired and he had to be fed through a tube.
Lewis was found dead on July 18, 2019, at the home where he lived with his adoptive parents in Tingley, Leeds.
The cause of death was given as peritonitis caused by an infection from his feeding tube. Bird was charged with murder following Lewis’s death.
At the start of the trial, prosecutor Richard Wright QC told the jury: “The death of Lewis Turner was not some freak infection that took the life of a healthy boy. It was instead the final consequence of a deliberate assault on Lewis by Alan Bird.”
Bird was Lewis’s natural father and he attacked his son on the night of September 29, 2001 at their home in Thorn Avenue, Dewsbury.
Paramedics found Lewis covered in bruises and “deathly pale”.
He was rushed to hospital where a scan revealed he had suffered the devastating injuries as a result of his brain being starved of oxygen.
Bird later admitted to a social worker that he was responsible for causing the injuries and had done so by holding a pillow over the child’s face.