A pensioner has gone on trial accused of killing his step-son almost 50-years ago, after the victim's brother - who was just three at the time - came forward and told police he had witnessed the murder.
David Dearlove, 71, had always claimed his 19-month-old stepson, Paul Booth, died after banging his head when he fell out of bed at their home in Stockton-on-Tees in October 1968.
But in 2015 he was arrested and charged with murder, when Paul's brother, Peter, spotted a faded family photograph on Facebook and came forward to describe how he had witnessed
Mr Dearlove smashing the toddler's head against a fireplace.
Despite being aged just three at the time of the alleged murder, Peter, recalled witnessing the horrific event through the living room door which was ajar.
Teesside Crown Court heard how Mr Booth had lived with the memory for almost half a century, but was prompted to come forward when he saw a picture that a relative had posted on Facebook of Mr Dearlove holding his baby brother.
Angered by the seemingly happy picture, he confided in a cousin what he had witnessed and she subsequently went to police who launched an investigation.
Mr Dearlove was arrested at his home in Great Yarmouth, Norfolk, where he lived with his wife of 36 years and charged with murder and child cruelty.
Opening the case, Richard Wright QC, prosecuting, said: "There was and is no doubt as to what medical condition caused the death of Paul Booth. He died because of a severe injury to his brain that had itself been caused by a fractured skull. The real issue then in 1968 as now nearly fifty years later in 2017 is what caused that injury?"
Despite being alone with the toddler at the time of the incident, Mr Dearlove was not arrested and a subsequent inquest recorded an open verdict, effectively closing the case.
Mr Wright told the jury: "So it remained for nearly 50 years until March 30, 2015. It was on that day that a cousin of Paul Booth contacted the police. She was making the call on behalf of Paul's brother Peter, the little boy who had been almost four years old on the night his brother died."
He went on: "Peter told the police that the death of Paul was not the result of an accidental fall out of bed.
"He had in fact seen how Paul came to be injured when he had crept downstairs to get a drink.
"Through a gap in the door into the sitting room he had seen David Dearlove swinging Paul
Booth around whilst holding onto his ankles and had watched as his step father smashed the little boy's head into the fire surround, causing the fatal injury to his skull by the impact.
"The death of Paul Booth had been no accident, it had been as the result of a deliberate act. It had been murder."
The court heard that Mr Booth had reported the incident to the police himself in the early 1990s when he lived in Birmingham and again around 2005, when he lived in Sussex, but the case was never taken up.
However when his cousin went to the police two years ago an investigation was launched.
Mr Wright said the catalyst for the complaint in 2015 had been when Mr Booth saw a photograph posted on Facebook of his dead brother being held by David Dearlove.
He said: "Peter contacted David Dearlove Jr and demanded that he remove the photograph and then spoke with his cousin Tracy about why he was so upset, telling her that he had seen David Dearlove swinging Paul by his ankles in the front room, then striking his head off the fire surround causing the fatal injury.
"He had been extremely scared of David Dearlove because the violence in the household extended not just to David Dearlove hurting Paul but also to him regularly assaulting Peter."
The court heard that Mr Dearlove allegedly subjected Mr Booth and his sister to violence and cruelty also, including locking them out of the house on freezing winter nights.
Mr Dearlove denies the murder and unlawful killing of Paul Booth and further denies three charges of child cruelty - defined as assault, ill treatment or neglect causing injury to health - in 1967 to 1968.
The trial, expected to last three weeks, continues.