Russians picked up her father near the front line almost 2 years ago. She hasn't heard from him since.

KYIV, Ukraine -- Yulia Khrypun, 22, hasn't seen her father, Serhiy, for almost three years. Most of that time he's been in Russian captivity, where she says she's worried he's been tortured and beaten.

Serhiy worked as a security officer at a farm in a tiny village near Tokmak, in the Zaporizhzhia region. On Feb. 22, 2022, he went on duty, unarmed, carelessly leaving his documents at home as he couldn't even imagine what would happen to him next.

Early in the morning on Feb. 24, Russia started a full-scale invasion of Ukraine. Within a couple of days, Serhiy saw Russian soldiers in the village where he worked, his daughter Yulia told ABC News. They could talk on the phone then.

"One soldier came to the farm and asked for some food," Yulia said. "He drank a cup of tea, my father told me, and then noticed a map of Ukraine on the wall. Dad showed him their location on that map and the guy was really astonished how big Ukraine is and had no idea where to go."

Later, a group of Chechen soldiers on a truck appeared in the village as the Russian troops occupied southern Ukraine.

"They settled in the farm, ate all the chickens, looted [a] local grocery shop," Yulia said, recalling what her father had said. "They held him captive in fact and he only managed to go outside at night to call me, his mom and sister. The ugliest thing was the Chechens' insults. They were drinking and then saying something like, "Oh, we haven't killed any Ukrainian yet, maybe we should kill Serhiy.'"

Yulia was staying in Dnipro, where she was studying and working. "I couldn't believe Russia really invaded. Of course I was extremely worried for my dad, but the worst actually happened next."

On March 22, her father called her to say that the Russians left the village, and although it seemed like good news, that was the last time Yulia spoke to her father.

"After I hadn't heard from him for a couple of days I started panicking," she said.

A little later, the owner of the farm where her father worked said her father had been captured.

"The videos from security cameras showed the other group of Russian soldiers stripping my dad of his clothes and shoes, apparently looking for some nationalist tattoos, which he doesn't actually have, then taking him and some of his colleagues into the truck and leaving," Yulia said.

For Yulia, life turned into a nightmare then.

"I couldn't eat because I knew my father wasn't eating," she said. "I wanted to sleep not in bed but on the floor, because I knew he was in awful conditions. I was like a vegetable, unable to talk."

She spent her days working and searching for any information about him through social media.

Amid her growing despair, she found relief in her friendship with another girl, Karina, who was also searching for her missing relatives.

"Then I felt like she was the only person who really understood me and we were in touch almost round the clock," she said.

Together they decided to set up a nongovernmental organization, Civilians in Captivity, to raise awareness about the missing people and pressure the Ukrainian authorities to do everything possible to return them.

From different people, who have been brought back so far, she learned about her father's destiny.

"Some men saw him in four different colonies in Russia where they were taken by trucks from Ukraine through the occupied Donetsk region," Yulia said. And in each place Serhiy apparently faced so-called "reception."

"On the first day the person is admitted to a prison, they are being beaten and tortured for like 24 hours, as I was told," she said. "The Russians use electric shocks, make people crawl on their knees and elbows, break their ribs, etc."

Ukrainian ombudsman Dmytro Lubinets added that during months of captivity in Russian prisons, some people have lost weight and suffered from a number of illnesses.

"One of those who we managed to return lost 77 kilograms in 5 months," Lubinets said during the international human rights conference in late December 2023.

The total number of Ukrainian civilians captured during the two years of invasion is a ballpark figure since Russia doesn't provide any details, but Lubinets said it's estimated that there are more than 25,000 people who've been captured.

Yulia Khrypun's NGO has worked with about 400 families who have been searching for their relatives and demanding they be exchanged.

The swaps of civilians are not regulated by international humanitarian law and the Geneva Conventions generally prohibit the capture of noncombatants. In Ukraine, there is still no separate institution for treating such cases, they are all part of the work of the coordination headquarters for the treatment of the prisoners of war.

"The very fact that civilians are being returned as part of the POWs swaps, and that these swaps take place during the actual fighting is a big achievement," Vitaliy Matvienko, a representative of the headquarters, told ABC News. "Every time it is a separate operation in an unpredictable environment. The names of people who are working on it are kept secret."

The Ukrainian authorities have not disclosed many details about this process, due to the sensitivity of the issue.

Yulia Khrypun said she hopes she gets a call from her farther every time she hears a prisoner swap is happening.

"And when I don't get it it's the worst feeling ever," she said.

To support both hope and mental health she went to a therapist and began to play sports.

"I keep waiting for my dad. I know it will be still hard after he returns, there will be a bunch of other problems," she said. "But I keep going and sometimes my hope even helps me keep smiling."