A mother of nine and her boyfriend have been found guilty of causing the death of her baby son, who suffered 28 fractures during his short life and had been exposed to amphetamine and cocaine.
Five-month-old Eli Cox died in hospital on April 27 last year, two weeks after an incident at his home in on the Isle of Sheppey in Kent, England.
He suffered a "catastrophic" injury while in the care of Katherine Cox and Danny Shepherd.
His heart stopped beating and he stopped breathing some time after 5pm on April 13, Maidstone Crown Court heard.
His heartbeat was restored, but he was not able to breathe unaided.
Eli had suffered brain damage and two small round bruises were found at the back of his head.
Prosecutor Jennifer Knight said a post mortem found that death had been caused by a "shaking or shaking impact type" head injury and that Eli "had also suffered skeletal injury on many different occasions leading up to his death". Tests also found traces of the drugs.
Cox, 33, and Shepherd, 25, who were the only adults present when Eli was injured, were both found guilty of causing or allowing the death of a child between April 12 and 28, and causing or allowing physical harm to a child.
They were also both convicted of possessing the Class B drug amphetamine.
Sentencing will take place on a date to be fixed for a psychiatric report to be prepared.
Cox and Shepherd - who calls himself Pickle - moved in together in November 2015 after they started dating that summer.
A crowd of neighbours, some of whom tried to help, had gathered at the house by the time the ambulance arrived at 5.35pm.
Cox later told police she had called the ambulance after seeing Eli lifeless on the bed with "ooze coming out of his nose" and Shepherd was performing adult CPR on him.
Police found five bags of amphetamine drugs in the form of white powder when they searched a shed in the couple's garden on April 14.
Post-mortem examinations showed Eli had oxygen deprivation to his brain, suggesting he had suffered a trauma, bleeding around his optic nerves and a brain injury.
The oldest of his fractures was possibly from between seven to nine weeks before his death. A hair sample showed he had been "regularly exposed to amphetamine and occasionally exposed to cocaine", Ms Knight added.
Shepherd told police that neither he nor Cox had deliberately or accidentally injured Eli or lost their temper with him.
The court heard there was a long, thin wooden stick, which was dubbed "Pickle's beating stick". But the couple said it was banged to get the dogs into the garden and was not used as a weapon.
Libby Clark, from the Crown Prosecution Service (CPS), said afterwards: "This has been a difficult case to prosecute due to the complex medical evidence and challenges in establishing the involvement of either or both of the defendants in relation to the fatal injury caused to Eli.
"When the trial started, our case was that either Danny Shepherd or Katherine Cox had caused Eli's injuries and the death, or were aware that there was a significant risk of serious physical harm being caused to him, and failed to take reasonable steps to prevent this.
"During the course of the trial and in light of the evidence given, it became possible to say that Danny Shepherd was the perpetrator of the injuries to Eli, including the assault which led to his death.
"The fatal injury and older fractures identified by one of the medical experts showed very significant similarities. This considerably undermined the defence case that they were caused by another person."
Detective Inspector Ivan Beasley, of Kent Police, said afterwards: "The death of a child is never anything less than tragic but the circumstances behind Eli Cox's passing are especially upsetting for those of us who share a compassion for others.
"None of us will ever understand what compels people to cause harm to children, and it is unfortunately true to say that Eli suffered more than most and was robbed of his life before it had barely begun.
"Katherine Cox and Danny Shepherd maintained their innocence throughout but the jury saw through their lies. Only they know the true extent of the abuse Eli was put through, which is simply unthinkable to most members of society including parents who would do anything to protect their children from harm."