His lawyer, Khaled Zabarqa told the BBC he was freed after serving his sentence.
Israelis saw the young age of Manasra and his cousin at the time of the attack as evidence that they had been indoctrinated by propaganda.
After the stabbings, Manasra fled the scene and was hit by a car. A graphic video widely shared on social media showed him as he lay bleeding profusely on the street and an Israeli bystander jeered and heckled.
This footage provoked outrage in the Arab world and many assumed the boy was dead. However, days later Israeli authorities published a photo of him being treated in hospital.
Later, Manasra was convicted of attempted murder and sentenced to nine-and-a-half years in jail.
Doctors say that he developed schizophrenia behind bars and tried to harm others and himself.
Repeated legal appeals for his early release were denied on the grounds that he was convicted of a terrorist offence.
Since his release, his family has declined to speak to journalists.
“Until now, Ahmed’s health state is unknown, and the family’s priority is to diagnose and treat him and follow up on his health situation to lessen the side-effects that Ahmed might face,” Khaled Zabarqa said.
Amnesty International and the Israeli NGO, Adalah, accuse the Israeli authorities of breaches of international law throughout Manasra’s case.
They point to his interrogation at age 13 – without a guardian or lawyer present.
Leaked video showed Israeli security staff shouting and insulting him as he became visibly distressed.
“Manasra’s rights were systematically stripped since his imprisonment. He has only been allowed to see his immediate family through a glass wall, without any physical contact,” Adalah said in a statement.
“He has been completely denied the right to education and stripped of other basic rights. His right to dignity was violated, including through two years spent in solitary confinement, and his right to health was disregarded due to ongoing medical neglect by the Israel Prison Service.”
The prisons service says that all detainees are held in accordance with international law and that any allegations of abuse are investigated.
Recently released Palestinian prisoners say that conditions inside Israeli jails have become much harsher since the deadly Hamas-led assault on southern Israel in October 2023, which triggered the Gaza war.
Many of those freed during the recent ceasefire in Gaza appeared thin and sick, and some needed immediate hospital treatment.
They have described beatings, severe overcrowding, insufficient medical care, scabies outbreaks, and poor sanitary conditions.
Israel’s far-right National Security Minister, Itamar Ben-Gvir, has boasted of ordering tight restrictions on security prisoners.
Last month, a 17-year-old Palestinian boy from the occupied West Bank who was held in an Israeli jail for six months without charge died after collapsing, in unclear circumstances.
Walid Khalid Ahmed became the first Palestinian child to die in Israeli detention.
An Israeli doctor who observed the post-mortem examination found that he was suffering from extreme malnutrition.
