Updated at 5:30 a.m. on July 4 to include news of Dmitry Kolker's death.
A Siberian spectral imagery scientist battling late-stage cancer was arrested in hospital and brought to Moscow on accusations of treason, the Tayga.info news website reported Thursday.
He died in custody two days later.
Dmitry Kolker, Ph.D., headed the Novosibirsk State University’s quantum optical technologies laboratory, which partners with Germany’s Max Born Institute and France’s National Institute of Metrology.
“They took a sick man, who was practically dying and feeding through a tube in his vein, from a private hospital,” his son Maxim Kolker told Tayga.info.
He said Kolker, 54, was accused of sharing state secrets with China.
Kolker was known to have given lectures, including on laser spectroscopy and laser imaging, detection and ranging (Lidar), at a Chinese university.
“There was an FSB officer with him everywhere, who flew with him to China, forbidding him to speak in English and to give the lecture in English,” Maxim Kolker said, referring to a Federal Security Service operative.
Novosibirsk’s Sovetsky District Court ordered Friday to place Kolker in pre-trial detention until Aug. 29, Russia’s state-run TASS news agency reported.
If found guilty of high treason, Kolker faced up to 20 years in jail.
But Kolker’s family had expressed fears he may not survive his incarceration.
On Sunday, Maxim Kolker and his sister Alina Mironova said they received a telegram of Kolker's death in pre-trial detention at 2:40 a.m. Saturday.
The cause of his death was not specified, but Mironova said earlier that Kolker was suffering from stage IV pancreatic cancer.
"This shouldn't have happened. The man was unable to pass on to a better world near his family," Mironova wrote on social media.
"They didn't even let the family say its goodbye," Maxim Kolker added.
According to Tayga.info, Kolker had been flown to await trial at Moscow’s notorious Lefortovo prison.
The outlet reported that his arrest was accompanied by searches at his family’s apartment, where security agents seized his equipment.
Kolker was the latest in a string of Russian scientists, academics and journalists to be suspected of passing state secrets to foreign countries in recent years.