A man is facing jail after admitting killing a baby boy by gripping him, shaking him and throwing him into a Moses basket - causing fatal head injuries, a court heard.
Paul Rich pleaded guilty to the manslaughter of three-month-old Patrick Bradley during a "spur of the moment" attack after becoming "frustrated" while caring for him.
The 53-year-old had tried claiming Patrick's fatal head injuries were caused when he dropped him from his arms into his Moses basket.
But on the eve of his murder trial at Bristol Crown Court, he offered a new basis of plea to the charge of manslaughter in which he accepted he had unlawfully killed Patrick.
Sally Howes QC, prosecuting, told the court the fatal injuries were inflicted in the early hours of March 25 2017 when the defendant was looking after the baby at the child's home in Swindon.
Patrick's mother and father were out that evening and at 3.15am - shortly after the infant suffered the fatal injuries - Rich dialled 999.
He told the operator: "It's the baby. Just got him out of his cot. He's not looking right to me. His eyes are semi-open and he seems all floppy to me."
Patrick was taken to Great Western Hospital in Swindon and later transferred to the specialist intensive care unit at Bristol Children's Hospital.
He never recovered from his injuries but his life support was withdrawn on March 30 and he died in his mother's arms a short time later.
The cause of death was given as "severe head injury".
When Rich was arrested on suspicion of attempted murder, he told officers: "I was just caring for the child. I am just a family man."
Later, he added: "I wouldn't hurt a child."
Ms Howes said the defendant had at an earlier stage pleaded guilty to manslaughter on the basis he had accidentally dropped Patrick from his arms into his Moses basket, which was on the floor, from a height of 3ft to 4ft.
"He wasn't thinking what he was doing with the child and he was frustrated and very tired," Ms Howes said.
"According to one expert, this explanation would be unique if it was accepted by the court."
She said that basis of plea was not acceptable as he was trying to suggest Patrick's death was accidental but he had suffered compression to the ribs, shaking and a severe blunt force impact to the head.
"The experts cannot say what happened. The only person that can say what happened is the defendant," Ms Howes said.
"The broad conclusion of the medical experts is the injuries occurred at the time of or shortly before Patrick's collapse.
"It is the Crown's case that all the injuries were inflicted and sustained during the same assault upon Patrick.
"It was a spur of the moment, no question about it - one of the factors finding the plea to manslaughter acceptable."
Rich, of Sandy Lane, Shrivenham, near Swindon, had been due to stand trial accused of murder and two charges of causing grievous bodily harm with intent on the infant between March 23 and 26 2017.
But following his guilty plea to manslaughter, the prosecution accepted the not guilty plea to murder and the two other charges were ordered to lie on file.
Adam Vaitilingam QC, defending, said by the time of the fatal attack his client had been without sleep for 19 hours.
"Nothing I say is in any way diminishes the awfulness of what he did," he said.
"The court should know - perhaps not surprisingly, given his obvious attachment to the child - he is devastated by what he did, devastated by what happened to Patrick.
"We are dealing with a few seconds of exasperation or frustrated behaviour, which involves him throwing Patrick into the Moses basket.
"The phrase 'end of his tether' would be a fair description in this case."
Mr Justice Soole adjourned sentencing until Wednesday morning and remanded Rich into custody.