A 10-month-old baby boy died after suffering a "devastating and irrecoverable brain injury" when his nanny allegedly lost her temper and shook him, a court has heard.
Joshua Paul was being looked after by childminder Viktoria Tautz, 34, at his home in Culross Close, Haringey, north London, on August 29 2014 when he collapsed.
He was rushed to North Middlesex Hospital before being transferred to Great Ormond Street Hospital but died on September 1 in his parents' arms, Blackfriars Crown Court heard.
Tautz, of Holly Park Road, Haringey, denies one count of manslaughter.
Opening the trial, prosecutor Zoe Johnson QC told the jury: "On August 29, for whatever reason, the Crown's case is that something snapped in her and for a short while she lost her temper with Joshua and assaulted him causing all those injuries.
"Her account of what happened whilst she was looking after Joshua does not explain Joshua's injuries and therefore something occurred - a shaking and/or impact - which the defendant has not revealed."
Tautz, who was arrested on September 5 2014, said in interviews that she had played a "horse riding game" with baby Joshua but he had not had any accidents and denied that she had shaken him.
Prosecutor Ms Johnson told the jury: "Joshua died because of a head injury that caused bleeding in his brain, bleeding in his eyes and other brain and spinal injuries.
"You will hear from a number of medical experts and a group of these have concluded that Joshua suffered that head injury as a result of being shaken or shaken with an impact to the head.
"The defendant, Ms Tautz, was in sole charge of Joshua at the time of his collapse and thus it is that she is charged with the manslaughter of Joshua Paul."
Ms Johnson said Tautz began working for the family on June 16 after Joshua's mother Pearl Vijayan returned to work.
She said she had been working in "quite testing circumstances" - confined to a one-bedroom flat while looking after Joshua which she was instructed not to leave.
She was not given a key to the property and told not to bathe the baby boy, the court heard.
Joshua's mother left the baby in the flat with Tautz on August 29 at 8.40am and said he was "happy and playing" at the time.
London Ambulance Service was called at 9.07am by a neighbour after Tautz emerged from the flat holding Joshua, who was unconscious and not breathing, and pleaded for help.
Paramedics arrived at 9.11am and found the baby boy lying on his back on the hallway floor while Tautz was "very distressed".
The childminder told medics that he had been crying, shook twice when he was picked up "as if he was convulsing" and then went floppy and stopped breathing.
A series of medical tests were conducted at Great Ormond Street Hospital.
"The results were all in keeping with a very sick child but they did not provide any explanation for Joshua's sudden collapse and those brain and spinal injuries," Ms Johnson told the jury.
Doctors told Joshua's parents on August 30 that their child had suffered "a devastating and irrecoverable brain injury from which he simply would not recover", his brain was not showing signs of activity and his heart "could stop at any time".
He suffered three cardiac arrests at Great Ormond Street Hospital and died at 10.55pm on September 1.
Joshua, who was born around 10 weeks early and needed help with breathing, was said to have a large head for his age but scans had not shown up anything of concern, Ms Johnson said.
She said experts had ruled out natural diseases and other conditions as an explanation for Joshua's collapse and injuries.
The trial, which is expected to last four weeks, continues.
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