The stepfather of five-year-old Charlie Dunn who drowned at a water park has been jailed for more than seven years.
Paul Smith, 36, was heard swearing and blaming others after Charlie Dunn, who could not swim and was on the child protection register, went missing while unsupervised at Bosworth Water Park in Leicestershire in July last year.
High Court judge Mrs Justice Jefford sentenced Smith to five years and two months for Charlie's manslaughter with a consecutive two-year term for threatening to petrol-bomb the home of a witness and a further four months for driving while disqualified.
Charlie's mother, Lynsey Dunn, 28, was given an eight-month suspended jail term after admitting neglecting Charlie in a separate incident in 2015 when a neighbour prevented the then four-year-old from driving a toy car on to a main road.
Smith, from Tamworth in Staffordshire, initially denied any wrongdoing in relation to the death of Charlie but pleaded guilty earlier this month to unlawful killing on the grounds of gross negligence.
A jury at Birmingham Crown Court was told other children pulled Charlie from a lagoon after 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."
The court heard Charlie was allowed to "fend for himself" in a pool which had signs warning parents that youngsters must be supervised.
Passing sentence, Mrs Justice Jefford said: "I do not doubt that Lynsey Dunn and Paul Smith had genuine love and affection for Charlie."
Rejecting Smith's assertions that he had been an "impeccable" stepfather, the judge told him: "Nothing could be further from the truth.
"One father (in the lake at the park) had to explain to another that Charlie was not his son.
"You were completely indifferent to Charlie's whereabouts and safety.
"This was not a case in which there was an isolated and momentary lapse in care and supervision."
The judge said of the children aged 10, 11 and 12 who found Charlie and pulled him from the water at least 20 minutes after he was last seen: "This must have been a horrific experience for them and I take this opportunity to praise the care that these young boys showed for Charlie."
During her sentencing remarks, the High Court judge said Smith appeared to have "simply given no thought" to Charlie's safety.
Prior to sentence, it emerged that Charlie was made the subject of a social services child protection plan in November 2012.