YEREVAN, Armenia — Yuri ­Asryan lived alone on his small farm in a village in southern Nagorno-Karabakh. The 82-year-old was a quiet, well-liked man, locals told an Armenian lawyer who documented Asryan's death after videos surfaced depicting atrocities in the conflict over this disputed region in the Caucasus.

The farmer did not flee the village, Azokh, when Azerbaijani forces swept in to seize it from ethnic Armenian control during the recent six-week outbreak of fighting. His last moments are shown in a video that surfaced on a Telegram channel this month: He is held down by men in uniforms resembling those worn by Azerbaijani troops, one of whom saws into Asryan’s neck with a knife in an apparent decapitation.

Asryan has one surviving sibling, his sister, Maria, 80, who used to visit him every summer.

Human rights groups say hundreds of videos showing atrocities by troops on both sides have been posted online in the month since a cease-fire deal halted the fighting over Nagorno-Karabakh, an enclave within Azerbaijan’s borders but under ethnic Armenian control.

Amnesty International has verified 22 videos but stressed that they are not representative of the hundreds circulating on social media. Among the crimes, the organization identified two beheadings of Armenians and an execution of an Azerbaijani border guard.

The hostility between Azerbaijan and Armenia goes back decades, festering during the Soviet era and erupting into a separatist war in the late 1980s that ended with Armenia gaining control of Nagorno-Karabakh and seven surrounding regions. Decades of negotiations have failed to resolve the conflict.

After heavy fighting broke out in late September, Azerbaijan regained the seven regions and part of southern Nagorno-Karabakh. Russian peacekeepers have been deployed under the cease-fire deal.

The videos underscore the enduring animosity that rekindled the recent six-week conflict, ­fueled by nationalist rhetoric, disinformation and propaganda — all amplified on social media.

One video depicts Genadi Petrosyan, 69, a villager from Madatashen, being beheaded by what appeared to be Azerbaijani soldiers. The video is filmed by someone standing over Petrosyan as he lies on the ground. A kneeling, helmeted soldier decapitates him with a knife. The killer’s face is away from the camera. Another video shows Petrosyan’s head placed on the carcass of a pig.

Like Asryan, he lived alone. He was unmarried and had no children. His only brother lives in Ukraine, according to Armenian lawyer Siranush Sahakyan.

Sahakyan identified the two slain men from the flood of videos depicting extrajudicial killings, beatings and other mistreatment of prisoners, and the desecration of bodies. Many of the videos have surfaced on Telegram channels since the cease-fire. According to her, more than 60 videos show violations of the rights of Armenians.

She said that Petrosyan’s village was evacuated the day before the Azerbaijani forces entered but that he tried to return and was captured.

In another video, the bodies of 19 unidentified soldiers, four with their hands bound, are displayed with their trousers pulled down. It is not clear how they were killed.

Other videos appear to show Azerbaijani troops beating and kicking captured Armenian soldiers. Azerbaijan has charged four of its soldiers with committing an insulting act on a grave or a corpse, after what authorities said were intensive investigations of the videos.

Denis Krivosheev, Amnesty’s research director for Europe and Central Asia, accused both sides of “depravity and lack of humanity” showing a “deliberate intention to cause ultimate harm and humiliation to victims.”

Sam Dubberley, head of Amnesty’s Citizen Evidence Lab, which has been working to verify the videos, said that although a large number of videos had come to light, it had been able to verify the authenticity of only 22 so far, including the two cases of decapitation, other executions, the mistreatment of captives and the desecration of bodies from both sides.

Dubberley said it had been difficult to geolocate the videos because little recognizable terrain is visible. Amnesty instead consulted a forensic pathologist, who ran technical tests that showed that the videos had not been digitally manipulated and confirmed that the actions shown in the beheading videos were “consistent with decapitation.”

They also found the uniforms, flags and language to be consistent with what the videos claimed to show, down to the patches on Azerbaijani troops’ jackets that display their blood groups.

According to Amnesty, 11 videos it has verified show violations by Armenian forces, including cutting the ears of dead Azerbaijani soldiers, as well as seven violations by Azerbaijani forces.

The office of Azerbaijan’s prosecutor general, Kamran Aliyev, said in a statement that the acts seen in the videos were “unacceptable and contradict the mentality of the Azerbaijani people” and that perpetrators will be prosecuted.

Aliyev said earlier that his office was conducting an investigation into the inhumane treatment of both Azerbaijani and Armenian forces as well as the footage shared online, Agence France-Presse reported.

“There are many fake videos. But we must say frankly that there also are videos which could be authentic. . . . Azerbaijan is a law-based state and we are reacting to such facts,” he said.

Dubberley said Amnesty was unable to confirm the nationalities of many people in the videos.

Sahakyan, the lawyer, cited videos showing eight ethnic Armenian civilians being taken prisoner, six of whom were mistreated, including by beatings with metal rods. She said that in some cases, the videos were sent to the family members of soldiers using their own phones or via Facebook.

“These videos are shared to terrorize people and gain a psychological advantage. The main motive is ethnicity,” she said.

Armine Abrahamyan, 37, a university research head who lives in Yerevan, spotted her three paternal cousins in an Azerbaijani video on Nov. 15, four days after they disappeared.

Brothers Mkhitar Abrahamyan, 42, and Khachik Abrahamyan, 28, and cousin Artashes Safaryan, 25, who has an intellectual disability — all civilians — had driven to Nagorno-Karabakh to get winter clothes for one of their wives, who is originally from the enclave. They set off two days after the cease-fire deal was signed.

They are thought to have been kidnapped on the road leading from Armenia to Stepanakert, the region’s administrative hub. The video shows the three, as well as another man thought to be a taxi driver, in the back of a van being ordered to recite phrases in Russian.

“Karabakh is Azerbaijani,” they are forced to say, as well as being told to recite phrases abusing Armenian Prime Minister Nikol Pashinyan. Russian is widely spoken in both countries.

The men have not been returned, but officials have told the family that they are alive.

Human Rights Watch has urged Azerbaijani forces to observe the Geneva Conventions, which state that prisoners of war should not be subjected to violence or intimidation. It said this month that it was investigating videos on social media purporting to show abuse of Azerbaijani prisoners. It said Armenia is also holding some Azerbaijani prisoners and at least three foreign mercenaries.

The rights group has also accused both sides of potential war crimes over the use of banned cluster munitions and indiscriminate rocket attacks on civilian populations.