Diaa, a middle-aged father and husband, was a polite host at his family home in one of the refugee camps in central Gaza. But you could see his pain.

Please come in. This is Abdullah's room.

Abdullah was his 19-year-old eldest son. On 2 August he was shot dead waiting for the daily opening of one of the food distribution sites run by the Gaza Humanitarian Foundation (GHF). It started operating in Gaza in May, established by Israel and the US and protected by the Israeli military, the IDF, and armed American security guards who are special forces veterans.

In Abdullah's empty bedroom, Diaa hugged his son's school bag.

My darling boy. His smell is still on it. May God have mercy on you, my son, forgive you, and accept you in the highest ranks of Paradise, God willing, with the Lord of the Worlds.

Diaa blames himself. The night before he said to me, 'Dad, I want to go.'

I told him, 'For God's sake, I don't want you to go tomorrow, please don't go.'

He said, God willing, everything will be fine, Dad.

Of course it's an awful feeling, as if I was the one who killed my son, as if I was the one who sent him to his death.

But we needed that aid. I gave up my eldest son so he could feed his siblings, his father and his mother.

Gaza is gripped by a famine caused by Israel restricting food and other vital supplies. The only time that aid agencies and commercial shippers were able to get in adequate supplies was during the ceasefire that started on 19 January this year. That stopped abruptly when Israel imposed a total blockade on 2 March and two weeks later went back to war.

The global body that assesses food emergencies, the IPC, said in its most recent report in August that the famine had reached Gaza City. Israel's prime minister Benjamin Netanyahu says there is no famine in Gaza, rejecting the overwhelming evidence presented by the IPC as an outright lie. The IPC is globally respected as an impartial and expert body. Netanyahu says Israel is not responsible for any shortages.

He blames ineptitude at UN agencies in Gaza and has repeatedly accused the UN of doing nothing about the systematic theft of food by Hamas. The UN denies his allegations, arguing that its consignments are bar-coded and traceable. Israel, it says, has never provided evidence of the allegations of systematic theft, despite repeated UN requests.

Famine is why Palestinians in Gaza, many of them young men like Abdullah, are prepared to risk their lives at the GHF sites to get food.

It is nearly two years since Hamas killed 1,195 people in southern Israel and took 251 hostages. Forty-eight Israelis are still in Gaza. Perhaps 20 of them are thought to be alive. It remains Israel's biggest trauma since its independence in 1948.

Israel's response has been to inflict the biggest trauma Palestinians have suffered in the same nearly eight decades. The Israelis continue to argue they are acting in self-defense in Gaza - a narrow strip of land that is now in ruins, and has seen the killing by Israel of at least 65,000 people, according to the Hamas-run health ministry, including more than 18,000 children. Israel rejects these figures but they are generally considered reliable by international organizations.

Abdullah was a bright young man. Sticky notes above his desk display reminders to himself to aim for 95% in his exams. Judging by the photos his father provides, he dressed smartly, with a sharp haircut and an expectant smile. He must have seen possibilities ahead in his life, even in Gaza, a place where life was hard even before the war. Now it is reduced to a struggle to survive Israeli attacks and the famine.

Abdullah's neighbor, Moaaz, a friend since childhood took up the story of what happened the day he died. They went together to GHF site 4, the only one in the center of Gaza, following the instructions of IDF soldiers about the correct route to take. To get ahead in the deadly race for food, many Palestinians arrive at the GHF sites long before dawn. Moaaz and Abdullah were waiting near a ruined house less than 500 meters from the site.

Then Abdullah said he had to deal with a call of nature, and moved, Moaaz says, about 30 meters away. That was when he was shot dead. Moaaz said he ran through heavy fire to get to his friend. He lived around 10 more minutes.

Diaa told us about his son, and how hard it is to live and stay alive in Gaza.

In Gaza we are a peaceful people. Abdullah was a young man like any other. May God have mercy on him. He didn't get the chance to fulfill any of his dreams.

We asked the IDF specifically about the death of Abdullah. It did not respond but told us it does not deliberately fire at innocent civilians. GHF's lawyers say its security contractors do not open fire either. They say they are not aware of any credibly documented instance of their ever doing so - and that no one has been shot dead at a GHF site, or within sight of one.

Abdullah's story comes from the film that we have just broadcast, called Gaza: Dying for Food, produced by Panorama and BBC Eye. It is an investigation into hunger in Gaza, and the killing around the food distribution sites run by the GHF. Dying for Food looks at just one part of Gaza's humanitarian catastrophe. We have established how so many Palestinians are being killed seeking aid. It is a worthy subject for a half-hour television film. A comprehensive account from every angle would need a series.

Reporting and producing the film has been a considerable challenge. That is because Israel does not permit the BBC, or any other news organization, to send teams into Gaza to report freely. Palestinian journalists inside Gaza have done heroic work, without which we would know much less about what has been happening there in the past two years. According to the UN Human Rights Office, at least 248 of them have been killed by Israel.

On Dying for Food I was the reporter, the public face of a big team of journalists. I wrote the script, but I did not interview Diaa or Moaaz about the killing of Abdullah. I wasn't present when the filming took place of the dead and dying in hospital emergency departments, of miles of rubble and Palestinians desperate to grab some food while the IDF and armed American security men working for GHF were said to have opened fire. I was able to talk to the interviewees who weren't in Gaza, either face to face or via video.

It is not the way the BBC, or any other group of journalists and filmmakers would choose to work. A fundamental rule of journalism is to narrow the distance between the reporter and the story. It was drummed into me when I was a BBC trainee journalist assigned to the Belfast newsroom during the Troubles in the winter of 1984-85. An acerbic news editor, using a tone that might get him into trouble these days, told me to leave the building to use my own eyes and ears, and to talk to people.

It is impossible for a foreign correspondent to report the war in Gaza like that, as Israel has kept the gates of the Gaza Strip firmly closed. The IDF allows some news teams short and heavily supervised visits. I have done one, for about three or four hours, in the first month of the war. It let me see the destruction firsthand, and to talk to soldiers.

One IDF officer started by telling me that they worked hard to safeguard the lives of noncombatants. Even in the first few weeks of the war, Israel was being accused of ignoring its legal obligations to protect civilians. Then the officer trailed off and in disgust told me that all the Palestinians were guilty, not just the Hamas units that had led the 7 October attacks. If they weren't guilty, he said, they would have found a way to overthrow Hamas.

To get round Israel's ban on our entry into Gaza, we commission local freelancers who are still able to operate on the ground. Our team had long conversations with them about where to film, who to interview and what to ask. We needed to know about the backgrounds and relevance to the story of potential interviewees and where filming would be an acceptable risk to take in a warzone where nowhere is safe.

From a distance, BBC journalists directed the teams we used in Gaza. We reviewed and verified the material we received, examining closely the data embedded in videos that shows when and where it was shot. Just communicating with people in Gaza is hard. Digital connections are patchy. It took several days for the story of Abdullah to be sent to London after it was filmed.

Connectivity out of Gaza is often weak or non-existent, as Israel has bombed mobile phone masts and internet hubs. The current Israeli offensive in Gaza made movement difficult and highly dangerous. One of the filmmakers we worked with in Gaza City went quiet for a few days while they moved their family somewhere they hoped might be safer.

As well as interviewing Abdullah's grieving, dignified father, and his friend Moaaz, who saw him die, in Dying for Food we spoke to Reem, a mother desperate to get food for her hungry children, whose husband was killed early in the war. He was also looking for food, more plentiful then but still dangerous to venture out to get it as Israel invaded and pummeled Gaza.

She was interviewed in a tent in Gaza City. We have not been able to contact her in the past week or so. We believe Reem might have taken her two children south from Gaza City to escape the ferocious offensive Israel has launched to capture the area. If so, it would be the sixth time they have been displaced. Most of Gaza's more than two million civilians have been displaced many times.

One way of getting information when physically you are not there to see it for yourself is to talk to witnesses. I interviewed an NHS doctor just back from Gaza called Tawfik Omar, who is a vascular surgeon in Coventry. Tawfik is from Egypt and spoke at length to patients and their families in Gaza. Vascular surgeons see a lot of blood. Tawfik was shocked in Gaza by an overpowering smell of blood in hospitals packed with the dead and dying who had been shot near aid sites.

The local people coming from the GHF points, he told me, are saying clearly that we can see the GHF security guards or the IDF personnel shooting directly at the crowds.

Dying for Food features two whistleblowers, who didn't want to be identified. One was a lorry driver for a GHF logistics subcontractor. We called him John and hid his identity because he is worried that his safety might be compromised if it was known that he had spoken out. He told me that another potential whistleblower had been silenced by threats from former colleagues.

There are only three GHF aid points, compared to 400 that existed when the UN was distributing aid. John told us they felt like military bases on the front line, not places where humanitarian aid was given to those who need it. He told us that every night he did his work, it was with the background of heavy gunfire. John was so shocked by what he saw that he secretly recorded videos with his mobile.

His videos were part of the material we used to establish a pattern of the IDF's use of live fire to control crowds, an intrinsically lethal technique. On a day when more than 20 people were killed near the single GHF aid site in central Gaza, we were able to use John's video taken that night to help establish what was happening.

It shows heavy fire coming from an IDF position just behind site four. The bullets were hitting an area where we established that hungry people, in their thousands, would often gather near a bridge over a dried-up river bed that leads to the entrance of the site.

Even though we were not physically in Gaza, our team analyzed John's videos (and many others) using open-source intelligence, a way to check events and corroborate testimony by using the latest techniques and software to sort through the wealth of data and video that is available online. We spoke to five ballistics experts and used software that analyzes the sound of shooting on videos, to help establish the trajectory of bullets.

The data on the number of deaths at GHF sites comes from a body called Armed Conflict Location and Event Data (ACLED). It collects and analyzes data from warzones and is funded, among others, by the United Nations, the European Union, the US, and European countries including the UK.

ACLED's data shows that since the GHF began its operations, at least 1,300 Palestinians have been killed at, or around, its sites, mostly by IDF fire. Across Gaza, Palestinians were being killed seeking aid in the year before GHF arrived at an average rate of 30 per month. Since its sites opened, that has risen to 500.

The IDF denies the killing. It told us that it is not aware of hundreds of fatalities caused by… [its] …forces at distribution points. It says these figures are inflated and false.

The other whistleblower we interviewed was an IDF soldier. He too wanted to be anonymous as he is still an active reservist, though he was having doubts, like many other Israelis, about the morality of what he is being asked to do. When he was mobilized after the 7 October attacks, he was convinced like thousands of other soldiers that he was fighting to safeguard his country. Now he worries he is fighting to help preserve a war that Prime Minister Benjamin Netanyahu needs to stay in power.

Michael told me how concerned he was that IDF soldiers communicated their wishes to thousands of Palestinians by firing live bullets.

Yes, it concerned me a lot. Because the moment they won't listen to the shots, they'll start running at us, and then we need to decide what we're doing with a thousand people on their way to the base.

Michael said the GHF aid operation was chaotic and badly planned. He says his unit did not kill Palestinians seeking food aid by luck.

The IDF didn't address our questions about Michael's account of red and green lines.

It says it's learned lessons after civilian harm was reported at aid sites and that updated instructions were passed to[its] forces.

Volker Türk, the UN High Commissioner for Human Rights also spoke to us. We have had clear evidence of hundreds of people being killed trying to get access to these sites and mostly by Israeli military, which is totally unacceptable and that is a very grave breach, not only of international humanitarian law but also international human rights law.

It is extremely important that those who commit war crimes, those who committed crimes against humanity are held to account. They need to be brought to justice.

The current offensive is aimed at forcing up to one million people out of Gaza City. It suits the plan pushed by Benjamin Netanyahu's hardline allies to seize the Gaza Strip for Jewish settlers - and force Palestinians out.

The current Israeli offensive is rationalized as a necessary measure for national security; however, the dire humanitarian toll continues to attract international scrutiny and criticism. Amidst accusations of war crimes on both sides, the humanitarian implications of the conflict's escalation remain a grave concern, emphasizing the urgent need for a resolution to prevent further loss of innocent lives.