For 22 days, Nouri Jabarov and his family lived in a Mariupol basement, catching and eating pigeons to survive and waiting for a break in the bombing and shelling to brave the street in search of water.
During one of those runs to a nearby well, Nouri said he witnessed three of his neighbours die.
Warning: This article contains images and details readers might find distressing.
"There was no food, we were catching birds, that's how we survived," he said.
"For water, we had to go about 500 metres, but it was very hard. The risk was high because of constant shelling. Once a shell killed three people 50 metres away from me, and we ran back.
"They died instantly, blown to bits."
Mr Jabarov emerged from his basement bunker to help bury his neighbours the following day.
"Because the day they died, Azov soldiers were shooting near the sea and Russians were shooting back. That day we didn't go there. The next day we went there in the morning and buried them. We took a shovel — me and another man," he said.
"Near a park, we found a place where the ground was softer, and buried them there."
Mr Jabarov was sheltering with his partner Victoria, their 12-year-old son Artem and several neighbours, but in the early hours of March 18, the time to leave Mariupol arrived.
"We had been sitting in that basement, hoping that our building won't get hit. Then we heard an air strike," he said.
"It landed next to the building ... and half of the building was destroyed and then two shells hit the porch and we ran away barefoot, as fast as we could. We ran for our lives."
The group would be forced to walk 20 kilometres to the town of Mangush.
Mr Jabarov said, on the way, they encountered Russian soldiers.
"They wanted to shoot me down. My arm is burned from a pot, from cooking, and they thought I fought on the Ukrainian side," he said.
Other Mariupol residents who have escaped have told the ABC Russian soldiers searched their phones, deleting any images or videos from inside the city.
But Mr Jabarov was prepared.
"They searched, but I did a smart thing. I had a flash card in my phone. So I uploaded all the videos and photos there and removed everything from the phone memory. And the flash card, I hid it in my shoe, under an insole," he said.
After nearly two months of Russian attacks, no electricity, no communication networks or regular food and medical supply deliveries, there is reportedly just one location in Mariupol not under complete Russian control.
For Mr Jabarov, news of the city's final stand was "the hardest day".
"We lived there peacefully, everything was alright, we had work. And now we lost our home, we lost everything," he said.
Mariupol would be Putin's biggest prize
Vladimir Putin has claimed victory over the city, but Ukrainian fighters and civilians are believed to be holding out in the city's Azovstal iron and steelworks.
Ukraine maintains its last defenders in Mariupol will not surrender.
The capture of Mariupol would be the biggest victory for Mr Putin in his war so far and deliver Russia a continuous land corridor from its border to the Crimean Peninsula, cutting Ukraine off from the Sea of Azov.
Mariupol's representative in Ukraine's parliament Serhiy Magera told the ABC his beautiful town was in ruins.
"The town could be rebuilt, but the human lives are lost forever. I feel sorrow for the children, for everyone," he said.
"Words cannot describe the feeling when you face the massacre of your own town and its dwellers, when you see bodies of civilians lying along the roads and pavements. It's a nightmare."
Air strikes hit residential areas in Mariupol as well as hospitals and theatres where children and civilians were taking refuge.
Russia has denied several of the attacks, but they were an early indication of how vulnerable civilians in Mariupol, and across all of Ukraine, would be during the heaviest battles in this war.
Whether or not Mariupol has completely fallen to Russia, international law says civilians should be protected from targeted and indiscriminate attacks.
The laws of war also require both sides to allow humanitarian aid to reach civilians and for those people to be allowed to leave war-torn areas.
Part of the investigation into what has happened in Mariupol will look at whether or not its citizens were afforded those rights.
The importance of the flash card
Organisations including Amnesty International and Human Rights Watch have investigators on the ground in Ukraine working to establish details of the battle for Mariupol.
This work relies on testimony from people like Mr Jabarov and on any shred of original evidence that has been gathered in Mariupol and smuggled beyond the city limits.
Investigators will take that testimonial evidence, any video and photographic documentation, as well as other information like the location of military units and targets at the time, and figure out if the civilian deaths were proportionate or if they constituted a possible war crime.
With so little information available from inside Mariupol, efforts to get material out are hugely significant.
The ABC has seen countless videos and photos from Mr Jabarov and worked to independently verify several of them.
Some of the material was of an extremely graphic nature, including an image that shows three deceased people at the base of an apartment building.
Piecing together this material, evidence from other witnesses, open-source data and known details of the attacks in Mariupol will help investigators build a larger picture of what happened there.
Human Rights Watch senior crisis and conflict researcher Belkis Wille has been in Zaporizhzhia interviewing Ukrainians escaping Mariupol.
She heard stories from older Ukrainians or people with disabilities who were not able to leave their top-floor apartments without working elevators.
"So they instead spent their weeks upstairs in their apartment with their windows blown open in ... minus 8-degree temperatures and they were just sitting there looking out their window terrified as they saw fires and explosions going off," she told the ABC from Ukraine.
Ms Wille will work to establish the facts around some of the most notable moments in the battle for Mariupol.
"There are potentially specific attacks that need to be examined, like the attack on the theatre, like the attack on the maternity ward," she said.
"I would presume that there are other attacks, large-scale attacks that have killed civilians, and there would need to be proper investigations into every one of those to assess the extent to which those were lawful and the extent to which whichever side carried out the attack, minimised civilian casualties as much as possible."
Another moment in the battle for Mariupol being investigated is the alleged attack on the mosque of Suleiman the Magnificent and his wife Roksolana in mid-March.
Mr Jabarov said he was near to that site when a shell hit "near the mosque" and returned to film the damage. His testimony and video will help piece together what the impact really was.
The search for the missing
Now in Warsaw, Mr Jabarov and his family need to find a place to call home, while desperately trying to reach those they were forced to leave behind.
The family believe Victoria's brother and mother stayed in Mariupol and have no idea if they are alive.
Ukrainian authorities have released estimates of the possible number of civilian deaths in Mariupol, but humanitarian groups say there is very little independent information available to try and verify those claims.
"We have no sense of how many people have died," Ms Wille said.
"For everyone who has remained in the city, I think we have to presume that they have lived through extreme suffering. Our concern for everyone who's remained in the city is extremely high."
Mr Jabarov is Azerbaijani and so he has been told he is not allowed to stay in Poland. His wife and son are Ukrainian, but he does not want to leave them.
The family escaped the horrors of Mariupol, but now they are again in limbo — unsure where they can go and stay together.
"So many suffered and died. Not only me, but all the people of Mariupol, we have no home, no town, nothing. We are left in air," Mr Jabarov said.
Asked why he took the great personal risk of smuggling evidence out of Mariupol, Mr Jabarov said: "To show what the Russian 'liberators' did in Mariupol."
