On the inside of his left arm was the invocation, “be patient”, in Turkish. On the outside of his left hand, the Turkish word for “hope”.

Hope is a word that aptly described him, his sister Dilan Biyik told Al Jazeera. He was also optimistic.

Although he found it challenging to find stable work in Turkey, Buyuksu, a Turkish citizen of Kurdish descent, was always looking forward. He spoke frequently about trying to build a future for himself outside of the country.

“He wanted to settle in Europe and build a new life there. He wanted to get a residence permit and live there,” Biyik told Al Jazeera.

On September 27, 2022, he made a surprise video call to his family from the Greek island of Kos, an idyllic tourist hotspot home to about 40,000 people. He had made it to Europe without being intercepted by the Greek coastguard.

“We didn’t know he was going that day,” said his sister.

She spoke to her brother frequently via video call while he was on Kos. He stayed there for 23 days, spending time with a childhood friend, Ali Safak Polat.

“He called us almost every day. We were worried,” she said.

But he remained positive, smiling broadly in calls from Kos’s main town.

“He kept telling us that everything was going to be fine.”

On October 20, Buyuksu told his sister he was going to take a ferry to Athens.

But the next day, Polat called Biyik and said her brother never made it onto the ferry to Athens. He was apprehended by Greek police and loaded into a black van in the port, Polat said. Neither heard from Buyuksu again.

About 10 days later, the Mugla police station in eastern Turkey called, asking Buyuksu’s relatives to identify his body.

The Turkish coastguard had found him barely alive in an inflatable life raft, adrift about three miles southwest of the Turkish city of Bodrum.

Underneath his tattoos, bruises swelled and spanned to his neck, back and face.

The life raft was packed with 15 other people, all Palestinian refugees. Several in the group had similar bruises and wounds. One had a broken arm. Buyuksu died before they made it to Turkish shores.

Lawyers in Greece and Turkey and the Bodrum Chief Public Prosecutor’s Office allege that Buyuksu was illegally pushed back from Kos. They say he was another victim of violent and illegal expulsions occurring on Europe’s borders.

Biyik also blames Greece and calls her brother’s death a “murder”.

“Every refugee who ‘violates’ the borders is a criminal in their eyes and they think they have the right to do anything to them,” she said. “They kill people in a very cold way and throw them into the Aegean Sea. There is no more space in the cemeteries in our country where the bodies of unidentified refugees are buried.”

Greece maintains that it does not engage in illegal pushbacks along its borders. However, the practice has been documented many times via testimony, video and geolocation. It has been decried by human rights groups, the Council of Europe, the International Organization for Migration, the UN Special Rapporteur on the human rights of migrants, and the UNHCR.

The Turkish coastguard reported that Buyuksu was declared dead at about 5:20 in the morning.

The Hellenic Coast Guard did not respond to Al Jazeera’s requests for comment on the allegations.

The Palestinians who were on the life raft with Buyuksu later told Turkish authorities that upon their arrival on Kos, they were gathered up by people they identified as “Greek soldiers” and held. They said they were stripped naked, robbed of their phones and valuables, and beaten for hours. They said they heard someone screaming in Turkish in an adjacent room.

Al Jazeera has reviewed leaked documents from the Bodrum Chief Public Prosecutor’s Office that carried troubling statements by the Palestinian refugees.

“From what we heard, they were using violence and beating this person. The sounds of the Turkish citizen suffering and screaming were coming to the room we were in. Additionally as far as I could understand from the sounds, the [Turkish citizen] was being tortured by electrocution,” one said. “I could hear the sounds of the device used to deliver electricity. They continued the torture through the night.”

The Palestinians said in the early hours of the morning, they were taken to the sea, along with Buyuksu. They state they were forcibly boarded onto a Hellenic Coast Guard boat. At sea, they watched the coastguard inflate a life raft. All 16 people were tossed one by one onto the raft, and left abandoned in the Aegean, they said.

Investigation into Buyuksu’s death

More than two years after his death, Buyuksu’s family and lawyers say they still have no information on whether Greece has opened an investigation.

The Spanish newspaper El Pais, which reported on the incident in December, said Buyuksu’s legal team fears that neither Greece nor Turkey, countries that have long had political disputes, want the case to go further as they are enjoying a moment of good relations.

An autopsy conducted by the Forensic Medicine Institute of the Turkish Ministry of Justice, and reviewed by Al Jazeera, concluded that Buyuksu died as a “result of extensive intra-soft tissue bleeding along with multiple rib fractures due to general body trauma”.

“It is unanimously agreed that there is a causal link between the trauma exposed to and his death, and that there is no other common cause in the death,” the report stated.

The Bodrum Public Prosecutor’s office sent a request to the Greek Judicial Authority for assistance in investigating the death in January 2023. According to the documents reviewed by Al Jazeera, as of July 2023, they had received no response.

In November, legal organisations in Turkey and Greece – the Progressive Lawyers’ Association and the Legal Centre Lesvos – released a statement demanding information from Greece about the status of an investigation.

In Greece, the preliminary steps in such an investigation would be conducted by judges who would file a recommendation to the prosecutor on whether there was a need for a full investigation.

“Probably a preliminary investigation is on in Greece, but we’re not informed officially,” said Vicky Aggelidou, a lawyer at the Legal Centre Lesvos. “This was another illegal pushback from the land, as many others we have monitored. I hope the investigation will proceed and accusations against the Greek coastguard will be made.”

At the time of publishing, the Greek Ministry of Justice had not responded to Al Jazeera’s request for comment.

Having spent years consulting rights groups and lawyers, Biyik is running out of hope.

“I couldn’t even experience my pain because we are constantly fighting for justice,” she said. “After my brother’s perpetrators are found and punished, then I can start to mourn.”