The parents of the Palestinian boy burned alive by Jewish extremists have condemned what they say is a legal manoeuvre to evade justice by one of his killers.

Mohammed Abu Khdeir was seized on the street by Yosef Haim Ben David and two minors who can't be named on July 2, 2014 in a random revenge attack for the killing of three Jewish youths by Palestinians. They beat him with a wrench and poured petrol down his throat before setting him on fire.

The Jerusalem District Court found the two minors guilty of murder yesterday but accept a petition by David's lawyers to delay his sentencing on the grounds of insanity.

He will not be convicted of the murder until a psychiatric evaluation has been carried out.

"It made me relive my son's murder, I went back to the time they burned him – we haven't had any justice for him and we won't," said Mohammed's mother, Suha Abu Khdeir. Speaking to the the International Business Times from the family home in Shuafat, East Jerusalem she said, "I was in shock when the verdict was announced in court, I am still in shock now – I can't really express it."

The two minors turned against David at the trial and attempted to blame him for the deaths. However, the court viewed a surveillance tape of the three preparing to carry out the murder by practising punches and strikes.

The teenager's father Hussein said he rejected the verdict and hoped the judge would dismiss a report purporting to show Ben David was insane. "Every time I go to the court and see the ones who burned my son, my heart burns," he said.

"How can the defendant, two days ago, a year and a half after the crime, bring a document claiming insanity? It's all lies and I worry that the court will free them in the end."

Ayman Odeh, a senior lawmaker from Israel's Arab minority, said: "The state is sending a clear message of forgiveness and understanding when it comes to Jewish terror."

Mohammed's murder led to outbreaks of violence across the region and contributed to the outbreak of the Israel-Gaza war on July 6.