Berlin (CNN)It was the evening of July 5 and Magdalena Freudenschuss hadn't heard from her partner all day. That was unusual, so she was worried.
Peter Steudtner, a human rights trainer, was at a workshop on IT security and mental health strategies for activists in Istanbul with several colleagues.
"We made calls to Turkey to find out what had happened, whether it was just an internet problem," Freudenschuss told CNN. "And then we found out through the consulate."
Steudtner had been detained along with another trainer and eight human rights activists, including the director of Amnesty International in Turkey, Idil Eser.
Three weeks later, all of them -- now known as the "Istanbul 10" -- remain in custody, accused by Turkish authorities of "committing crimes in the name of a terrorist organization without being a member."
Freudenschuss was allowed a brief phone call with Steudtner soon after his arrest, but "he couldn't tell me a lot," she said. "At that point we didn't foresee how long it would take."
At first, Steudtner and the others were kept in solitary confinement, but they have since been put together in one cell, Freudenschuss said.