A callous mother and father have been jailed for seven years each following the death of their seven-week-old baby.
Parents Adam Kightley and Jacqueline Parker inflicted horrific injuries on little Jamie Kightley, including all-over bruising and more than 40 fractures to his ribs and legs.
He died in hospital of respiratory failure and a heart attack after suffering severe brain damage.
Kightley, 24, and 21-year-old Parker were found guilty of causing or allowing the death of a child following a three-week trial at Nottingham Crown Court.
They were originally accused of murder, but the charge was dropped mid-way through the trial after jurors were told how the couple had 'hidden behind a wall of silence' - making it impossible to say exactly who had harmed Jamie.
The court was told the pair 'concocted' a 'malicious' story in which they claimed to have previously shown bruising to a local GP, who dismissed it as unimportant.
But Kightley, who admitted drinking lager and smoking cannabis the day before Jamie's death, accepted only he or Parker could have caused the fatal injuries.
However, both he and his partner insisted they had no idea how Jamie received them, and dialled 999 after waking up to find him ill.
Judge Mr Justice Baker said he was satisfied both Kightley and Parker shared a 'substantial level of culpability' in Jamie's death.
He added: "You were his parents with whom he lived and were responsible for his care and welfare. During his short life Jamie was subjected on at least two and probably three occasions to deliberate traumatic harm: the latter two episodes involving the gripping and shaking of him with sufficient violence to cause him to suffer bleeding to the areas of his eyes and brain, and the fracturing of his ribs and the bones of his legs.
"As a result of the final episode of violence, Jamie also suffered brain damage leading to his death.
"It is clear from the medical evidence in this case that the episodes of violence would not only have caused pain and upset to Jamie, but more significantly would have caused visible bruising to his body, which should at the very least have caused you to seek prompt medical attention.
"Instead, not only did each of you fail to do so in the days leading up to his death, but I am quite satisfied that in order to cover up for this failure you concocted a story in which you maliciously suggested that you had previously shown bruising to a local GP who had dismissed it as unimportant.
"Your individual failure to take even the most basic action led to the perpetrator being able to strike again, this time with fatal results. In this manner your culpability led directly to the death of your son."
Mr Justice Baker said that as a 'result of the stance both of you took' during police interviews and the trial, 'the identity of the perpetrator may never be known'.
Kightley was jailed for seven years while Parker received the same term in a young offenders' institution.