A Russian physicist arrested in Siberia on suspicion of treason has died after just a few days in custody, his family and lawyer have said. Dmitry Kolker, a 54-year-old diagnosed with stage four pancreatic cancer, was taken from his hospital bed in Novosibirsk on Thursday by Federal Security Service officers, who put him on a four-hour flight to Moscow’s Lefortovo prison. By Saturday, he was dead. “The last contact I had with my father was at 6:15 p.m. on the flight to Moscow. He said he was saying goodbye,” Maxim Kolker said, according to the New York Post. “The investigator said the conditions were good, with a refrigerator in the prison cell. What refrigerator? The man can’t eat, he is fed intravenously.” A quantum and laser specialist, Kolker had been detained over a series of lectures he’d read to students in China, the contents of which had been previously approved by Russian security agents. “These charges are absolutely ridiculous and extremely cruel and unusual to be levied on such a sick man,” Kolker’s son told Reuters. “They knew that he was on his deathbed and they chose to arrest him.”