The woman was interviewed in her home village of Rozhki, 350 km north of Togliatti, where her son served before being sent to Ukraine.
Aleksandrova says that even if he did get discharged from the army without saying a word about it, Russian authorities should not abandon him. She said her daughter-in-law said nothing about the discharge as well.
"I do not know what they are doing," she said referring to the authorities. "They say nothing to me."
The detained sergeant told earlier that he attempted to reach his relatives through various phone numbers. But his mother didn't talk to him.
"I usually hang up if I do not know the number. What if this is Ukraine's Security Service with threats? I do not talk to anyone. How do I know this is Sasha?" the mother of the detained soldier said.
Zinaida Aleksandrova believes Russian authorities should make more efforts to release her son and another detained Russian, Yevgeniy Yerofeyev. "I just want my son to come back as soon as possible," she said.
"I have not watched TV ever since. I just can't. Who can I believe?" she added.
Father of the detained sergeant Aleksandrov refused to speak to Reuters correspondent. Aleksandrov's wife has not returned phone calls.
As reported earlier, Russian TV had showed Aleksandrov's wife and Yerofeyev's father. They commented in much the same way that the soldiers had discharged from the army but had not said they had left for the Donbas.