Simferopol, Crimea - The men who abducted Seiran Zinetdinov must have been really tough. The bald, bull-necked and burly 33-year-old emanated the self-confidence of a man who has seen danger and knows how to handle it.

Yet Zinetdinov disappeared one evening in late May. His friends last saw him a short walk away from his house in the village of Lugovoe outside Simferopol, Crimea's main city, where he lived with his pregnant wife and parents.

Neighbours noticed a strange man watching him that day from behind a tree - and a purple car with transit license plates that drove off from where Zinetdinov was seen last.

Zinetdinov was the third activist from Ukraine House - a small political group that opposed the Russian annexation of Crimea in March - to go missing, and he has not been seen or heard from since.

The group protested the takeover of Ukrainian military bases by Russian forces and had hostile encounters with pro-Russian "self-defence" units - paramilitary squads that mushroomed shortly before the Russian annexation of Crimea and often enlisted former military officers, Cossacks, and people of ill repute.

Pro-Russian activists patrol the building of the Supreme Rada, the main government building in Crimea's adiministrative capital, Simferopol, during Russia's annexation of the Black Sea peninsula in March [Denis Sinyakov/Al Jazeera]

Six months after Zinetdinov's abduction, his mother has lost hope. "Nothing is going to help, he is no more," says Elmira Zinetdinova, an ample woman with bleached hair and desperation frozen in her eyes. "He'd find a way to get in touch if they had left him alive."

More missing

The three activists were not the only ones who disappeared without a trace or were seen being kidnapped after the annexation. At least 15 people have gone missing since March, according to a recent report released by the Human Rights Watch, the New York-based international rights monitoring group.

Their disappearances were part of a broader crackdown on pro-Ukrainian, anti-Russian activists and Crimean Tatars, a Muslim minority mostly opposed to the annexation.

However, the final number of those still missing is likely to be higher, HRW says. Soviet-era dissident and a most revered Tatar community leader Mustafa Dzhemilev says the missing number 17. Ukrainian authorities insist the number is 21.

"Unfortunately, some of these people have died," Andrei Lysenko, spokesman for SNBO, Ukraine's main security agency, was quoted as saying by media in mid-November.

Crimean Tatar Muslims attend the funeral of Reshat Amedov, 38, an activist whose body was found with traces of torture - a ducktaped plastic bag over his head, and a pair of handcuffs nearby [Denis Sinyakov/Al Jazeera]

The first death occurred in March, shortly after thousands of armed and reticent Russian soldiers wearing uniforms with no insignia appeared throughout Crimea, and the first self-defence squads started attacking pro-Ukraine activists, dispersing anti-Russia rallies and harassing critics and journalists.

Tatar activist Reshat Ametov, 38, was inspired by Mahatma Gandhi's ideas of nonviolent civil protest. During his one-man rally in downtown Simferopol in March he was forcibly taken away by three camouflage-wearing men, according to footage from ATR, Crimea's last independent television channel.

His naked body with evidence of torture - the head wrapped in plastic and a pair of handcuffs nearby - was found in the back of a village house one day prior to the March 16 referendum, in which 97 percent of Crimean residents voted to join Russia.

Mark Ivanyuk, a 16-year-old activist who supported the civil protests that ousted Ukraine's pro-Moscow president Viktor Yanukovich in February, was found dead in April outside a village in western Crimea. Authorities said it was a hit-and-run accident, but Ivanyuk's parents insist he was beaten to death by local police officers who did not like the teenager's adamant refusal to speak Russian.

Vladimir Maguylo, a commander of a 'self-defence' paramilitary unit in Simferopol, says officials are reluctant to dissolve the militias and Russian authorities have pledged to finance and recognise them [ Denis Sinyakov/Al Jazeera]

Edem Asanov, a 23-year-old Tatar man who was not politically active but expressed his anti-Russia views in social media postings, disappeared in the city of Yevpatoriya in late September. He was found hanged in an abandoned building six days later. Authorities claim it was a suicide stemming from personal problems, but to the family and the Tatar community the death looks suspicious.

The fate of the others who are missing remains unknown, and only six people have been released.

One, pro-Ukrainian activist Andriy Schekun, said he was abducted by a self-defence militia in early March and forcibly held in jail-like conditions for 11 days - along with several other detainees. In remarks shown on Ukrainian television, he said he was interrogated, abused, beaten, and electrocuted twice.

Crimea's pro-Russian head Sergei Aksyonov reportedly admitted that Schekun was taken by "Crimea's intelligence" for distributing "provocative" materials. Prior to the annexation, Aksyonov led a marginal nationalist party and was accused by Ukrainian officials of alleged links to organised crime in the 1990s.

Failed investigations

Aksyonov has repeatedly pledged to find the missing men and the culprits behind the kidnappings. He regularly meets with a group of their parents and human rights activists that collect information about the missing. Despite his pledges and a rotating team of investigators, there has been no progress in the search.

"We're going through a 10th investigator, and every time they start from scratch," says Zinetdinova as she leans over the counter of a tiny perfume shop her daughter rents in Simferopol while discussing her missing son. "I don't know what's there to look for, what can one possibly find now?"

Zinetdinova is part of a group of parents who respond to reports on missing persons in Crimea and check whether their disappearance has any political background - or is just a case of someone leaving their spouse or leaving the peninsula to avoid business disputes.

Bishop Kliment says the Ukrainian Orthodox Church has faced pressure after Moscow's annexation [Denis Sinyakov/Al Jazeera]

Ukraine has seen the most rapid deterioration of human rights in world in 2014, according to a report released by a rights watchdog.

Continuing conflict, internal displacement, and worsening economic conditions in the country mean it has dropped 19 places in the past year - and is now 44th most "at risk" globally, said the Maplecroft Human Rights Risk Atlas 2015, which was released on Wednesday.

Another abduction also sent shockwaves across Crimea in the fall.

On September 27, two men in black uniforms forced Islyam Dzhepparov, 18, and his cousin Dzhevdet Islyamov, 23, into a Volkswagen minibus outside the village of Sarasu in central Crimea. Both were observant Muslims and never participated in anti-Russian rallies.

Dzhepparov's father, Abdureshit, immediately contacted authorities and posted a message on a social networking website that went viral across Crimea.

While talking to police officers, he "could not understand whether I was being questioned or interrogated", the bespectacled, grey-bearded 55-year-old says over a cup of coffee in his unheated, empty house.

He says the police thought that the abduction was linked to his political activism and squabbles over land rights on the peninsula. Until 2013, Dzhepparov was deputy chairman of the Mejlis, an informal Tatar parliament, and had invented a semi-legal way of providing Tatars with land.

Abdureshit Dzhepparov's son Islyam and his nephew were kidnapped outside the Crimean town of Belogorsk [Denis Sinyakov]

Motives for abduction

In 1944, the entire Crimean Tatar community was exiled from the peninsula to Central Asia for their alleged collaboration with Nazi Germans. They were allowed to return in the late 1980s - only to find that they would not be compensated for lost land and property.

In response, Dzhepparov and other community leaders initiated "land grabs", the practice of seizing collective farm land that was later privatised through court rulings.

The central Ukrainian government tacitly allowed the grabs, but the new Russian authorities banned the practice, while self-defence units organised raids to destroy dozens of unfinished houses on seized land lots.

"They hinted that a lot depends on how I behave," Dzhepparov told Al Jazeera. Tormented by guilt over the abductions, he says he firmly believes his son and nephew are still alive.

There is, however, another explanation as to why they were kidnapped. In 2013, his nephew spent several months in Syria fighting against President Bashar al-Assad's forces. Moscow remains the last powerful ally of Assad's government and is eager to root out any fighters who take up arms against Damascus.

Dzhepparov is also part of the group that coordinates the search for the kidnapped and missing and maintains regular contact with the authorities. But he is sceptical about the new authorities and says he thinks the purpose of the abductions is "to instil fear, to create provocations, make the situation explosive".

"Their aim is to butcher us so that they can consume each body part separately," he says.