A former US soldier who foiled a 2015 terrorist attack onboard a high-speed international train in Europe is unable to take part in the ongoing trial due to health reasons.
Spencer Stone arrived in Paris, France, on Wednesday but was hospitalised upon arrival. He has now returned to the US, his lawyer confirmed on Sunday.
Stone, a former US Air force soldier, was one of three American passengers who subdued Ayoub El-Khazzani, the man accused of opening fire on a Thalys train travelling from Amsterdam to Paris on August 21, 2015.
El-Khazzani was allegedly armed with a Kalashnikov rifle. Two people were wounded.
The trial over the attack started on November 16 and is to last until December 17. El-Khazzani is charged with attempted murder and conspiracy to commit a terrorist act.
Three other men suspected of helping El-Khazzani are also on trial but face lesser charges of conspiring with terrorists and accomplices to attempted murder.
Stone and the two childhood friends he was travelling with, Anthony Sadler and Aleksander Skarlatos, the latter of whom is also an ex-soldier, were celebrated as heroes in France for their quick action and received the country's highest accolade, the Legion d'Honneur.
Sadler and Skarlatos respectively testified on Thursday and Friday. Skarlatos, 28, told the court that the attack "changed my life".
"In my mind, we were supposed to die that day," he added.
The defence's lawyer said Stone's absence deprived them of an "essential" witness and complained that they did not receive a "medical certificate".
Stone's lawyer said his client might testify later via videoconference.