Towards the end of our interview about his son Nadeem's short life, Siam Nawara says something unexpected. Nadeem, 17, was one of the two boys shot by Israeli forces whose deaths were captured on CCTV. The shootings took place at a Nakba day demonstration outside Ofer prison on the West Bank on 15 May, while the boys were posing no apparent threat to Israeli soldiers. The shocking footage last week provoked international calls for an investigation.

Israeli accounts of what happened on that day in the town of Beitunia, near Ramallah, have failed to explain the circumstances satisfactorily. At first it was alleged the boys had been shot in the midst of a potentially lethal riot, but that live ammunition was not used.

As human rights groups and media investigated the claims, it became clear that at the time they were shot, the boys were a long way from the soldiers and that their wounds were consistent with the use of live ammunition, which is permitted only as a last resort.

Then anonymous military sources, briefing the Israeli media, suggested that the footage might be "faked" or that the boys had been killed by a mystery Palestinian gunman whom Israeli soldiers had not seen. The muddying of the waters only compounded the grief felt by the boys' families.

Sitting at his home in a well-to-do neighbourhood of Ramallah on the West Bank, Nawara, 42, speculates that the soldier who shot his son might not be "able to sleep or comprehend what he has done".

He adds that, like his own son, the soldier who killed him was probably a boy himself, perhaps not much more than 19. "I [want to] believe that he wanted to pay his respects and offer his condolences and ask forgiveness for what he'd done," he says.

Nawara suggests that he could forgive this other boy because the true culprit is the officer who gave the order for Nadeem to be killed, who "should have known better".

In the Nawaras' home, the grainy and fleeting figure caught on a CCTV camera in the few seconds when he was fatally wounded – and since seen around the world – solidifies and becomes human again. The media shorthand of "stone-throwing youth shot by soldiers" is left behind as a more complex person is revealed.

Nadeem was not a child of the camps or the poor neighbourhoods but came from a solid middle-class home. His father is the proprietor of one of Ramallah's best-known hair salons, which is situated next door to his family's spacious apartment.

Nadeem went to one of the city's best schools, St George's, a private Christian college, although he was from a generally apolitical and Muslim family.

"I love my country and my people," says Nawara, "but I never thought about going to demonstrations." He adds that he had thought of emigrating with his family to the US or Canada.

Nadeem, his family says, was a joker who teased his mother, a young man who liked making videos and listened to western music by the likes of Lil Wayne and Justin Bieber.

His family has enlarged the last selfie that Nadim took on his phone, wearing a kefiyeh and with his baseball cap on backwards.

His parents show me his computer. There is Nadeem swimming and building a snowman, hanging out with friends, a teenager as interested in American culture as Palestinian.

There are no pictures to do with politics, of friends throwing stones, of demonstrations, or images saved from the news.

In that sense Nadeem was the child of the new Ramallah that has prospered amid an economic boom.

The images from his phone could as easily be describing a life lived in one of the Palestinian communities in the US – in Phoenix, perhaps, or in New Jersey or San Diego. The screen saver is of a fluttering American flag.

But Nadeem Nawara lived in Ramallah, a place where boys demonstrate against the occupation, wrapping their faces in scarves and throwing stones, dodging tear gas and plastic pellets fired by an army that too often also uses lethal force.

According to a report published by Amnesty International in February – Trigger Happy, Israel's Use of Excessive Force in the West Bank – the number of fatal shootings, often in the context of stone-throwing demonstrations, has been rising, with 27 killed last year.

Nadeem's death poses many questions, including why he was shot while walking near a building not far from Ofer prison with no weapon in his hand. And why he was there in the first place. Footage captured by CNN suggests that he threw stones that day but from the shelter of the building where he died.

His father cannot explain it, not least because he asked his son not to go to the rally. However, Nadeem did go after school, carrying his schoolbag – the same bloody bag in which, five days after his son's death, Nawara would find a spent 5.6mm bullet.

"That day he climbed up the pillar at the school to hang the flag. The headmaster told him to be careful and Nadeem joked he was 'going for glory'," Nawara said.

"His brother told me he was going to the Nakba day march. His mother knew and they had quarrelled. I went to his room that morning after he got up to give him his pocket money and said, 'Don't go to the rally, your mother is worried.' She was afraid of a stray bullet. I tried, but I knew that I had not convinced him."

Was it Nadeem's first time at such a demonstration? His father thinks so, but it is difficult to know.

There is a martyr poster made by the school pinned on the wall, but Nawara makes no attempt to impose any political narrative on his son's death that might help to explain it and give it meaning. Did Nadeem go to Beitunia and Ofer prison that day simply because – for a teenage boy – such things are exciting?

All that seems possible to know is that, on that day, Nadeem ignored his father's concerns. "His mother was so worried that day," recalls Siam. "I called him about 1.15. I said, 'Son where are you?' He said, 'I'm going to Ramallah.' I said, 'Son, don't forget what I told you.' He answered, 'OK. OK. OK. Don't worry.' "

Nawara heard the news from his brother a few hours later while in his salon. Nadeem had been shot and badly injured.

"After his death the mortuary called asking me to bring some clothes because his own clothes had been cut off at the hospital. I opened the [mortuary] fridge and there he was, naked. I dressed him – I never thought that I would have to dress my dead son. I believed that he would do that for me."

Nawara does not have much faith in the Israeli military investigation into his son's death, which has yet to be completed, not least following last week's anonymous briefings by security officials.

"I know that Israel has law, but when it comes to Palestinians that law is vulnerable," he said. "They [the Israeli authorities] can play with the facts."