A couple wept in court as they were convicted of the manslaughter of their two-year-old son who died after drinking methadone.
Riley Pettipierre died in hospital after drinking the heroin substitute from a beaker left in a bedroom at his family's flat in Belper, Derbyshire, last March.
A jury at Nottingham Crown Court found his parents, Sally Dent, 33, and Shaun Binfield, 45, guilty of his manslaughter following a two-week trial.
Following the verdict, Judge John Milmo QC thanked the jury for dealing with such an "emotionally charged" case. He told the jury: "This has been a distressing case and I'm afraid it has fallen to you to deal with it."
During the two-week trial, the jury heard Dent had a history of drug use going back many years and was prescribed methadone to try to rid her of the habit. Dent regularly sold some of her methadone to other drug addicts to make extra money and was struggling to kick her addiction, the court was told.
The jurors heard that a green and yellow child's beaker of the drug was left in the bedroom on March 12 last year so Dent could drink from it during the night if she needed it. The next morning Dent, who had taken heroin the night before, woke to find Riley unconscious next to her in bed after the toddler drank the drug from the beaker.
The couple told the court a cup was usually kept on top of the wardrobe in their bedroom but had been moved on that occasion because it was more convenient for Dent.
Binfield told the court he forgot to move the cup because he had got caught up with putting the family bins out and the childcare routine after getting up on March 13. He fought back tears as he admitted he missed three opportunities to move the cup, which the child must have managed to get hold of and drink from. Prosecutor Yvonne Coen QC asked him: "It's not the possibility then that you thought to yourself 'Ah, the methadone's in there still but it's safe', or are you saying 'I never even thought about the methadone at all'?" Binfield answered: "I never even thought about it."
Dent called 999 and paramedics arrived at the house to find Riley lifeless. His heart had stopped beating and his lips were blue, the court heard. The child was taken to hospital but was pronounced dead shortly after arriving and post-mortem tests showed that Riley had enough methadone in his blood, stomach and urine to prove fatal. He is believed to have consumed between 10ml and 20ml of methadone, the court heard.
The jury took just four hours to convict Dent and Binfield of manslaughter. Dent was also found guilty of a separate charge of cruelty to a child under the age of 16 for failing to keep methadone out of the reach of her child. Following her conviction, the court heard Dent had previous convictions for possessing Class A drugs with intent to supply, assault and prostitution. Judge Milmo adjourned sentencing until February 19.