ALMATY, Kazakhstan — Around 7:30 p.m. on the evening of Jan. 6, Yerlan Zhagiparov left his home to see what was happening nearby at the city’s Republic Square, a center of mass political protests. At 7:54 p.m., Mr. Zhagiparov, 49, called a close friend to say he had been apprehended by the National Guard. The phone cut out after his friend heard him screaming in pain.

When his family found his naked, mutilated body in a city morgue six days later, his right hand had been broken and his face was swollen and red. He was still handcuffed, with gunshot wounds near his heart and abdomen.

His family wants an investigation into who killed him. Since his remains were found, other people have begun to come forward with accusations of abuse at the hands of Kazakh authorities.

Nationwide protests that erupted Jan. 2 over a fuel price hike quickly turned violent — fomented, many eyewitnesses and rights advocates say, by provocateurs — and were met by a vigorous security crackdown. For weeks, little was known about the tactics used to subdue the protesters — labeled “terrorists” by the government — other than a “shoot to kill” order from the Kazakh president on Jan. 7.

But now, primarily through crowdsourcing, human rights groups and activists are beginning to document a reign of terror that got underway well before the shoot to kill order. Videos and testimonials gathered by the groups, as well as interviews The New York Times conducted with protesters and their family members, reveal what they say was a ruthless campaign of brutality and intimidation that quickly overpowered a surprising revolt.

In a report released last week, Human Rights Watch said the Kazakh security forces used excessive and lethal force on demonstrators on at least four occasions between Jan. 4 and Jan. 6 that led to at least 10 deaths and 19 people being injured.

Human Rights Watch’s researchers said the number of deaths attributable to the Kazakh security forces was likely to be much higher.

“There is ample evidence showing that security forces opened fire without any apparent justification, ” Jonathan Pedneault, a conflict and crisis researcher at Human Rights Watch, said in a statement, adding “The death toll from the violent crackdown is likely much greater.”

There is also evidence that detained people were abused.

Little information has been forthcoming from Kazakhstan’s tight-lipped, autocratic government. It took almost 10 days before it announced a tally of the killed and missing — at least 225 killed, including 19 police officers, and more than 4,000 wounded.

But from scattered anecdotal reports, rights advocates suspected a widespread campaign of brutality and intimidation behind the government’s sketchy figures. So they began crowdsourcing information, offering legal and logistical support for people who come forward with tales of missing relatives or abuse.

After fielding calls from across the country about protesters who had been arrested or taken away, Bahytzhan Toreghozhina, a human rights lawyer, started a spreadsheet where people could list missing loved ones.

“Our government has said 10,000 people were arrested for the violence,” she said. “We want to find these people.”

The list, updated regularly to reflect those found dead or imprisoned, currently has about 1,300 entries from across Kazakhstan. As of Jan. 22, it includes 970 people confirmed to be in detention, including 31 political activists.

The list of people killed has reached, 227, slightly higher than the official number announced by the state. The Kazakh branch of Radio Liberty has also started its own list of the dead, so far identifying 124 people who lost their lives, including an 11-year-old boy.

And as more stories emerge, rights advocates have little doubt that the total will climb as more families come forward with accounts like that of Mr. Zhagiparov.

Initially, thinking he was in police custody, his family was relieved, said his younger brother, Nurlan Zhagiparov, 44. As an amateur archaeologist whose passion had been discovering Bronze Age stone carvings, Yerlan Zhagiparov had never been politically active.

His family just assumed the police would check his documents and send him home, his brother said, adding: “Nobody expected that a military group would take him away.”

The Zhagiparovs are hoping for an impartial investigation, something that many Kazakhs are demanding after the most violent episode since the country declared independence from the Soviet Union 30 years ago.

“We want to know who these people are who shot him, who tortured him, who broke his hand,” said Mr. Zhagiparov, as his mother sat silently next to him. “These sadists are walking among us in the streets. They must be punished.”

The Almaty police did not respond to a request for comment, and neither did the State Prosecutor’s Office.

In an interview on Saturday on state television, President Kassym-Jomart Tokayev said there was a lot of “exaggeration” and “hysteria” regarding reports of torture. “We need to find the bandits, but we also need to find the perpetrators,” he said, adding that he would not “justify” improper actions of the police. “I assure you that the rights of citizens will not be violated.”

At the outset of the protests, the authorities blamed the violence on unnamed criminal groups, including some from abroad. At Mr. Tokayev’s request, the Collective Security Treaty Organization, a Russia-dominated military alliance of post-Soviet countries, dispatched thousands of troops in less than 24 hours.

The government’s claims evolved to include unnamed “terrorists,” but the authorities furnished little proof of foreign involvement, and no terrorist group has claimed a role in the uprising.

“The pattern of beating and torture are aimed at intimidation and also at extracting false confessions,” said Hugh Williamson, the director of Human Rights Watch’s Europe and Central Asia division. Rights groups pointed to the “confession” of a prominent Kyrgyz jazz pianist, Vikram Ruzakhunov, as a prominent example.

The authorities released a video in which Mr. Ruzakhunov, visibly beaten, says he had been paid to come to the protest and cause havoc. But he says he was in Almaty on business and was detained while trying to get back to Kyrgyzstan. He wrote on Instagram on Jan. 24 that he had sustained a chest injury, broken ribs, a concussion and multiple bruises during his detention.

He was far from the only protester to meet that fate.

Dauren Dostyarev, an electrician, was arrested on Jan. 4, the first day of protests in the nation’s largest city, Almaty. In an interview, he said he responded to a call on Facebook from an opposition group and joined a protest in the city’s west. When the police arrived he says he grabbed a megaphone to remind the crowd to be peaceful.

He was taken first to a local police station and then to the headquarters of Almaty’s Internal Affairs department, where he said he was kept in a basement cell and beaten for eight days. He said interrogators struck him on his genitals, used electric shocks and forced other detainees to beat him. He was told repeatedly that he would never come out alive.

“I was preparing for the end of my life,” said Mr. Dostyarev, who is 32 and recently married. He never had access to a lawyer or to medical assistance.

Asset Abishev, a member of the banned opposition group Democratic Choice of Kazakhstan, said he had also been taken off a bus on Jan. 4 on his way to the protest. He was arrested and tortured for four days, he said.

Yevgeny Zhovtis, the director of the Kazakhstan International Bureau for Human Rights and Rule of Law, which has been collecting reports of abuses, said that he received numerous reports of torture in temporary detention units. He said that fear of the government was so pervasive that he estimated only about 10 percent of the victims would dare to file a complaint.

Ms. Toreghozhina, the lawyer, raised alarm about reports of people who had been wounded in the unrest and then taken from their hospital beds to prison. A video from an Almaty hospital leaked to Radio Liberty seemed to confirm this.

This week, the government announced a state-sponsored commission, led by well-known human rights lawyer Aiman ​​Umarova, will look into the events, which residents of Almaty have dubbed “Qandy Qantar,” or “Bloody January.” But organizations like Human Rights Watch have called for a truly independent investigation, with international experts.

Laylim Abyldayeva, 34, said in an interview that her husband, Timur Kim, 38, had been driving near the city center on Jan. 9 with her brother to see what was going on. The men were stopped and searched, then released. But hours after Mr. Kim returned to their suburban apartment, riot police barged in and dragged him away for questioning.

He was brought back the next day, bloodied and handcuffed, as the police searched the apartment. Ms. Abyldayeva said he told her he had been beaten and threatened all night.

After an investigator told her Mr. Kim was accused of terrorism, he was taken away again. She has been searching for him ever since.

“My husband is innocent, he did not even participate in any protest,” she said in an interview in her sparsely-furnished apartment. She has been appearing with her children, ages 8, 6 and three months, on Instagram videos appealing for her husband’s release.

Before the protests, Ms. Abyldayeva said, neither she nor her husband paid much attention to politics. They ran a small business selling tables and chairs, while he worked as a computer repairman. But now, she said, she had lost faith in the state.

“They simply have a quota they need to fill to show people that there were terrorists,” she said. “My husband is not a terrorist.”