The boy, Nolan, died on Saturday “as a consequence of his poisoning”, the family's lawyer Florence Rault told AFP on Sunday.
Lidl's French arm said in a tweet on Monday: “We share the pain of Nolan's family and will seek to assure our support during their suffering.”
Rault said that Nolan had not “ceased to suffer” after consuming the burger in June 2011. A dozen other children were also poisoned from steaks purchased from Lidl at the time, but Nolan suffered by far the most severe effects.
“His limbs became deformed, his bones would break and he had to undergo different kinds of surgeries. He could not eat, swallow, speak or move because he had no more ability to coordinate,” she said.
Le petit Nolan, 10 ans, qui avait été intoxiqué par un steak haché acheté chez Lidl est décédé ce samedi > https://t.co/11vd0Li8KQ
— Le Parisien (@le_Parisien) September 14, 2019
Nolan, who was just under two at the time of the poisoning, was left paralysed and mentally handicapped. He is the only one of the victims to have died.
Suffering from diabetes, he was fed by a tube and had to take medication several times a day with frequent stays in hospital, Rault said.
“His body finally gave up… as a result of all the pathologies which only got worse,” she said.
'Right to decency and compassion'
In February, the manager of Lidl's supplier SEB-Cerf, Guy Lamorlette, 78, was sentenced by a court in the northern town of Douai on appeal to three years in prison, one of which was suspended, for the poisoning. He was also fined 50,000 euros ($55,000).
The appeals court confirmed a sentence first given to Lamorlette in June 2017 on charges of causing “involuntary injuries due to a deliberate breach of safety operations”.
At the time, Nolan's mother, Priscilla Vivier, had said she was content with the verdict, saying “even though it will not make my son come back as before… he can no longer be involved with beef.”
The quality manager at SEB-Cerf, Laurent Appere, was tried on the same charges and appeared in the early stages of the proceedings. But he then died of a heart attack. His family vehemently denied claims of a suicide.
Lamorlette's lawyer has said he was considering appealing the prison term with France's Court of Cassation, but Rault urged him to abandon this idea after Nolan's death.
“Nolan's parents hope that one day they will have the right to decency and compassion,” Rault said, adding the family was heavily in debt after paying for his medical needs and that Lamorlette had not paid damages.