A five-year-old boy was found drowned more than two hours after his mother and stepfather let him "go off by himself" to play in a pool at a water park, a UK court has heard.
A group of other children pulled Charlie Dunn from a lagoon after his stepfather Paul Smith was allegedly seen smoking and heard saying: "For f***'s sake, we're ready to go. I don't know where he f****** is."
A jury at Birmingham Crown Court was told Charlie, from Tamworth, Staffordshire in England, was found in a 1.4-metre deep lagoon at Bosworth Water Park in Leicestershire in July last year.
Smith, 36, and Charlie's mother, Lynsey Dunn, 28, both deny causing the youngster's death by gross negligence by permitting him to enter a bathing area unsupervised.
Opening the Crown's case, prosecutor Mary Prior QC alleged that Charlie, who could not swim, was supervised near the water by strangers - including a man who was mistaken for his father - after being left alone.
The QC told the jury: "Charlie Dunn drowned in the pool for children at the park known as the Blue Lagoon.
"No one knows how it happened, no-one knows why it happened, and at the time he died neither Miss Dunn or Mr Smith had any idea where he was.
"Charlie had been permitted to go off by himself. The prosecution say that Charlie died because he was not supervised by any adult.
"He was left alone in a busy park at five years old in circumstances where there was a clear and obvious risk that he might come to very serious harm leading to his death. It will be for you to decide in this case whether that is right."
Claiming the defendants had shown "ingrained and entrenched indifference" at the time of the tragedy, Mrs Prior added: "This case is not about parents turning their back for a minute whilst a tragedy occurs.
"We don't prosecute parents for unavoidable tragedies nor do we expect perfection in parenting.
"This is a gross failure to supervise not for seconds, and not for a few minutes, but for protracted periods of time in circumstances where the child was exposed to danger."
Jurors heard the couple were given a "warning" of what could happen in the summer of 2015, when a neighbour prevented the unsupervised toddler, then aged four, from driving a toy car on to a main road.
Another neighbour, the court heard, spotted Dunn inside a car - out of sight of her son - when the boy came "perilously close" to straying on to a road in October 2015.
It was also alleged that Dunn and Smith were berated by a woman during a visit to the water park about two months before Charlie's death.
The witness, the court heard, told the defendants "in no uncertain terms that she was not happy that the defendants were not supervising Charlie near to the water".
Both defendants are said to have replied that Charlie "would be all right".
The Crown allege the couple breached their duty of care to Charlie, causing or significantly contributing to his death by gross negligence.
Concluding her opening speech, Mrs Prior claimed the parents were unable to help with what happened to Charlie during the two-hour period "except for the odd minute" when he returned to their car for something to eat or drink.
The couple deny being grossly negligent.
Dunn told police she thought Charlie would have informed her if he was going into the water, which he was "terrified" of.
Her partner told officers he had watched Charlie from a distance "and that if there had been a problem he could have leaped across and got him".
Smith also denies a count of attempting to intimidate a witness.
Jurors were told the open air pool had signs indicating that children must be supervised, and was not required to have lifeguards because of its depth.
It also emerged that Charlie - whose mother and stepfather went with him to the pool at about 12.25pm - did not have any buoyancy aids.
Off-duty police officers and paramedics tried to save Charlie after he was pulled from the water at about 2.45pm.
His parents then allegedly told on-lookers he had only been out of their sight for five or 10 minutes.
After acknowledging that the death of Charlie must have caused the defendants unimaginable pain, Mrs Prior said of the pair: "Neither of them at any stage said 'It's my fault - this is all down to me'.
"Neither of them say 'Do you know, on reflection I should never have let my boy go off and play by himself'."
The case continues on Monday.