“Instantly I was able to identify Luwam, who is wearing the orange scarf I know very well - and her shoes, which can be partly seen,” she told the BBC.
The sisters are from Eritrea - and like many young people Luwam Gebru had fled the country’s indefinite military conscription that they feel denies them a future.
She had ended up in neighbouring Ethiopia in 2019, where she had refugee status. But being a refugee can be like living a life in limbo - and many choose to make dangerous journeys in search of new lives and opportunities.
Ms Mihret said her 24-year-old sibling had decided to risk traversing the war zone of Sudan to reach Libya last year, several months after the conflict erupted.
Sudan descended into chaos in April 2023 when former allies - the army and paramilitary Rapid Support Forces (RSF) - began fighting each other for control of the country.
Many foreign nationals were hastily evacuated - but some refugees already in the country and recently arrived migrants like Ms Luwam found themselves treated with suspicion and taken as prisoners of war.
“We didn’t hear her voice for almost a month,” says Ms Mihret.
“She had called once from Sudan and told us: ‘Don’t worry I have arrived in Sudan safely and we might reach Libya this week.’”
Her younger sister sounded confident that the people smugglers she had entrusted with her life would not let her down.
But nothing was heard of her for another five months - until the videos appeared on social media in April.
BBC Verify’s analysis of the footage suggests they were uploaded on 7 and 8 April.
A Sudanese army general refers to the 50 or so detainees on board a truck as “mercenaries from Somalia, Eritrea and Ethiopia”.
They appear to have been captured fleeing fierce fighting around the al-Jaily oil refinery, north of the capital, Khartoum, which has been in the hands of the RSF and is used as a base in the area.
In one of the videos, an army officer says the captives are being transferred to the army's Wadi Seidna military base, which is also north of the capital.
There have been unsubstantiated reports that foreign fighters are being used by the RSF - which may explain the hostility to the group from the army officers.
Social media
Luwam Gebru, in her orange scarf, was pictured with other foreigners in an image thought to be from April
Still photos of the group, including several with Ms Luwam in her orange scarf, show them crammed into a room in a warehouse.
Ms Mihret, who was also able to identify one of her neighbours from Eritrea among the group, said they have not been able to get any more information.
“We don’t know much, we are told they are under the custody of the Sudanese authorities.”
Other Eritreans have told the BBC they have relatives registered as refugees in Sudan who have gone missing and are reportedly being held by the Sudanese military.
Two of them left Eritrea together last year, arriving at a UN-run refugee camp in Kassala state in eastern Sudan in October.
Their families say that Yonatan Tesfaslassie, aged 17, and Edmon Kidane, 20, were then approached by smugglers.
Such traffickers, some of whom are alleged to be from the RSF, often target the young and newly arrived promising them a safe route out of Sudan for a fee.
Once en route they put pressure on them to ask relatives abroad to pay more money and then abandon them on the way.
In Mr Yonatan’s and Mr Edmon’s case, they were aiming for South Sudan when it seems they were abandoned by the smugglers and became separated.
It appears they had both made it to Wad Madani, in Gezira state, a city about 190km (118 miles) south of Khartoum that had been a safe-haven for many since the start of the war.
That was the last time Mr Yonatan’s family heard from him – when he said he was setting out with other migrants towards South Sudan.
AFP
Hundreds of thousands of people fled Wad Madani ahead of the RSF taking the city in December
His sister Winta Tesfaslassie later heard from those who managed to make it safely across the border that he may be among many migrants who were then arrested in the army-held town of Rabek a little further south.
Some of them, they said, were taken to the nearby town of Sinjah and others possibly to the town of Sennar to be held by the army.
“The entire family is so worried and we have no idea what to do, we feel helpless. We want to know if he is safe, he is too young to go through such an ordeal and he has nothing to do with the war in Sudan,” Ms Winta, who lives in the UK, told the BBC.
Mr Edmon’s family also last heard from him when he was in Wad Madani - though it appears he was detained in the city several weeks before it fell to the RSF.
“We were told by a smuggler he was held by the Sudanese army,” his sister Adiam Kidane, who is based in Angola, told the BBC.
The smuggler was their only source of information “but later he stopped answering our calls”, she said.
Adiam Kidane
A smuggler told Edmon Kidane's family that the young man was detained by the military in Wad Madani
“We couldn’t tell our mother for a long time but eventually we had to. She fainted the moment she heard we had no news of him. We are all in distress. We are constantly thinking what might have happened to him.”
Some reports say more than 200 migrants of different nationalities had been detained at a military facility in Wad Madani before the RSF advance - information the BBC cannot independently confirm.
It has since been reported that the detainees were moved with the army when it withdrew from Wad Madani.
The UN refugee agency says it has received similar reports about the detention by the army of asylum seekers and refugees. According to the UN, there are more than 147,000 Eritreans and around 70,000 Ethiopians in the country.
It told the BBC it was planning a verification mission to Sennar state, which includes the towns of Sinjah and Rabek, urging relatives of refugees who believe them to be in detention to report the information through the UNHCR Sudan’s help page.
Likewise the International Committee of the Red Cross (ICRC) said those with a family member missing in Sudan should open a case via its hotline or offices in the country.
“Helping families who lost contact with their loved ones to trace them is one of our major priorities. But our ability to do this depends on the access we have and the volatile security situation,” the ICRC told the BBC.
The Sudanese embassy in London did not respond to a BBC request for comment on the detentions of foreign nationals.
Despite international efforts to stop the fighting in which more than 15,000 people are believed to have been killed, the warring parties are unable to agree a ceasefire.
The three sisters who have spoken to the BBC about their missing siblings say it is an incredibly frustrating process to find out any information be it from the ICRC, UN or the military.
“Please help us, the UN, anyone… we are desperate,” said Ms Winta.
“We appeal to the Sudanese authorities to please, please allow them to call us to hear their voices.
“We beg the army to release them, these are innocent young people who left their country with the hope of reaching a safe destination in South Sudan.”
