Frances Inglis is alleged to have killed her son at his Hertfordshire care home
A mother accused of murdering her disabled adult son told the Old Bailey she wanted him to go to heaven rather than suffer "hell on earth".
Frances Inglis, 57, of Dagenham, Essex, denies murdering Thomas Inglis, 22, on 21 November 2008 and an earlier attempt to kill him on 4 September 2007.
She allegedly fatally injected him with heroin at his Hertfordshire care home.
Breaking down, Ms Inglis told the jury she believed the ordeal being suffered by her son was like being "tortured".
Ms Inglis is accused of giving her son the lethal injection after he was left helpless by serious head injuries.
She is said to have administered the fatal dose in November 2008 while on bail for a previous alleged attempt to kill him in September 2007.
Ms Inglis said every doctor she had spoken to, apart from the consultant treating her son, had confirmed her "worst fears".
"Tom has lost his life, didn't die, and would never be able to do anything himself," she said.
The Old Bailey has heard Mr Inglis was left helpless and unable to speak after suffering serious head injuries when he fell out of an ambulance in July 2007.
'Fight with police officer'
Ms Inglis said the family was told by a doctor that her son would die unless he had an operation to remove part of his brain.
She told the jury that she pleaded for the surgery not to take place, but that the operation went ahead.
The defendant said she believed her son was kept alive because he fell from the ambulance "while fighting with a police officer".
If Mr Inglis had died it would have "looked very bad for them", she said, before adding: "I know that the operation wasn't for Tom's benefit."
On Monday the consultant surgeon who looked after Mr Inglis at Queen's Hospital, Romford, Essex, told the jury that he had shown "little in the way of what seemed irrecoverable brain injuries".
"The early signs were about as good as we could have had at that stage," said the surgeon, Ragu Vindlacheruvu.
The doctor said in September 2007, on the day Ms Inglis had first allegedly tried to kill her son, he had seen him and was "pleased" with how he seemed.
The case was adjourned until Thursday after Ms Inglis broke down in tears while giving her evidence.