The parents of six-year-old Jack Adcock have spoken of their pain over his death as a doctor and agency nurse face jail for his manslaughter.
Nicola and Victor Adcock cheered as Dr Hadiza Bawa-Garba was found guilty of gross negligence which led to their son's death in February 2011.
It followed a guilty verdict for nurse Isabel Amaro on the same charge on Monday.
Ms Adcock paid an emotional tribute to her son on the steps of Nottingham Crown Court, saying he was "one in a million".
She said: "Our son Jack was a lively and energetic little boy. The room lit up when he walked in with his cheeky smile and his cheeky ways. He drew people to him like a magnet.
"Our life now is empty, painful and will never be the same again.
"To say that we miss him does not do justice to our strength of feeling - Jack was an amazing son and one in a million.
"We have always believed that someone needed to be held accountable for what happened to our son. The guilty verdicts will bring us some closure but the void that has been left in our lives will remain."
Bawa-Garba and Amaro were accused of "truly, exceptionally bad" treatment which led to the death of Jack, a youngster with Down's syndrome and a known heart condition.
Another nurse, Theresa Taylor, who was also involved with Jack's care at Leicester Royal Infirmary, was cleared after nearly 25 hours of deliberations at Nottingham Crown Court.
The prosecution claimed the medical team at the hospital "robbed" Jack, of Glen Parva, Leicester, of his chance of survival when he was admitted to hospital.
He was admitted suffering from vomiting and diarrhoea and later developed sepsis.
All three medics were accused of medical failings which led to Jack's death. A jury of six men and six women took five days to find Bawa-Garba, 38, of Leicester, guilty of manslaughter by gross negligence by a majority verdict of 10-2. Taylor, 55, also of Leicester, was found not guilty of the same charge.
During the trial, the prosecution said Jack died after a series of failings by medical staff, including Bawa-Garba's "failure to discharge her duty" as the responsible doctor.
Prosecutor Andrew Thomas QC said: "In short, she neglected her duty to care for Jack.
"It was not just a momentary lapse. The prosecution say that Jack's care was neglected over a protracted period of time: her failings were compounded by a failure to go back and reassess Jack despite clear indications that his underlying condition was continuing.
"These were not just simple breaches of duty, but really serious breaches amounting to gross negligence."
Bawa-Garba failed to recognise that Jack was suffering from septic shock and when he collapsed, she momentarily stopped life-saving treatment after mistakenly believing he was under a "do not resuscitate" order.
The error was picked up by a junior doctor after CPR was stopped for around a minute.
Nottingham Crown Court heard that Bawa-Garba had confused Jack for another patient she had treated earlier in the day, in what prosecutor Mr Thomas described during his opening as a "remarkable error".
He accepted the break in resuscitation would not have had any effect as Jack was already past the "point of no return", but added the "relevance is that it shows that she had simply not given Jack sufficient attention during the day, to the point that she did not even recognise who he was".
The court also heard Amaro accepted she breached her duty of care but denied that any of her failings significantly contributed to the youngster's death.
Mr Thomas said her record keeping was "woefully incomplete" and she failed to monitor Jack's vital signs.
He said: "The prosecution say that these were major failings which contributed significantly to the overall deficiencies in Jack's care.
"If nurse Amaro had brought any of these to the attention of her senior nursing and medical colleagues, this should have led to urgent reassessment and initiation of further treatment to improve Jack's condition.
"It was a needless death."
During the four-week trial, the court heard evidence from Ms Adcock, who said she was "hysterical" after her son collapsed with his lips turning blue.
"He was just lying there. It looked like he was fast asleep," she said.
Bawa-Garba and Amaro, 47, of Manchester, will be sentenced at a later date.
Andrew Furlong, interim medical director and children's orthopaedic surgeon at the University Hospitals of Leicester NHS Trust, said improvements had been made since Jack died.
He added: "We cannot bring Jack back and under the circumstances saying sorry does not seem enough. Nevertheless, we are deeply sorry and would like to again send our condolences to the Adcock family."