A Briton fighting in Syria "turned the gun on himself" to avoid being taken prisoner by so-called Islamic State, Kurdish sources have told the BBC.
Ryan Lock, 20, from Chichester in West Sussex, died on 21 December during a battle for the IS group's stronghold of Raqqa.
He was fighting as a volunteer with the Kurdish armed fighting forces, the YPG.
The YPG told the BBC that "trace of a gunshot wound was found under the chin", suggesting suicide.
Sources said five fighters came under siege by IS - also known as ISIS - in the village of Ja'bar, and they showed "considerable resistance" before they were killed.
After the bodies were retrieved examinations showed that "it seems that the British fighter committed suicide in order not to fall captive with Isis".
A report said the gunshot wound indicated "that the gun made contact with the bottom of the chin".
"This suggests that the fighter committed suicide," it concluded.
Kurdish rights activist Mark Campbell, from , told BBC South: "Ryan Lock may very well have turned his own gun upon himself rather than be taken prisoner by ISIS.
"There are no words to describe the bravery required to take such an action.
"ISIS were robbed of a predictable macabre propaganda opportunity by Ryan's action.
"I personally believe he deserves the very highest of military honours for such outstanding bravery in the face of such a barbaric enemy."
Mr Lock, a chef, had travelled to Syria in August having told friends and family he was going on holiday to Turkey.
Earlier on Tuesday his body was transported into Iraq in preparation to be flown back to the UK.
In a statement to the BBC, his father Jon Lock, from Chichester, said: "Since we heard the devastating news of Ryan, it's been pretty tough, especially the difficulties surrounding the repatriation.
"We are grateful to the YPG for bringing him home."
Mr Lock's body had been in the hands of IS militants.
The volunteer, who attended school in Havant, Hampshire, became the third British man to die fighting alongside the Kurds against so-called Islamic State.
The Foreign Office continues to advise against all travel to Syria.
A country of fertile plains, high mountains, and deserts, Syria is home to diverse ethnic and religious groups, including Syrian Arabs, Greeks, Armenians, Assyrians, Kurds, Circassians, Mandeans and Turks. Religious groups include Sunnis, Christians, Alawites, Druze, Mandeans, Shiites, Salafis, and Yazidis. Sunni Arabs make up the largest population group in Syria.
In English, the name "Syria" was formerly synonymous with the Levant (known in Arabic as al-Sham), while the modern state encompasses the sites of several ancient kingdoms and empires, including the Eblan civilization of the 3rd millennium BC. Its capital Damascus and largest city Aleppo are among the oldest continuously inhabited cities in the world. In the Islamic era, Damascus was the seat of the Umayyad Caliphate and a provincial capital of the Mamluk Sultanate in Egypt.
The modern Syrian state was established after the end of centuries of Ottoman control in World War I as a French mandate, and represented the largest Arab state to emerge from the formerly Ottoman-ruled Arab Levant. It gained independence as a parliamentary republic on 24 October 1945 when Syria became a founding member of the United Nations, an act which legally ended the former French Mandate – although French troops did not leave the country until April 1946. The post-independence period was tumultuous, and a large number of military coups and coup attempts shook the country in the period 1949–71. In 1958, Syria entered a brief union with Egypt called the United Arab Republic, which was terminated by the 1961 Syrian coup d'état. The Arab Republic of Syria came into being in late 1961 after December 1 constitutional referendum, and was increasingly unstable until the Ba'athist coup d'état, since which the Ba'ath Party has maintained its power. Syria was under Emergency Law from 1963 to 2011, effectively suspending most constitutional protections for citizens. Bashar al-Assad has been president since 2000 and was preceded by his father Hafez al-Assad, who was in office from 1970 to 2000.
Syria is a member of one international organization other than the United Nations, the Non-Aligned Movement; it has become suspended from the Arab League on November 2011 and the Organisation of Islamic Cooperation, and self-suspended from the Union for the Mediterranean. Since March 2011, Syria has been embroiled in an uprising against Assad and the Ba'athist government as part of the Arab Spring, a crackdown that contributed to the Syrian Civil War and to Syria's becoming one of the most violent countries in the world. Since the start of the war in 2011, a number of self-proclaimed state entities have since emerged on Syrian territories, including the Syrian Opposition, the of Iraq and the Levant.