In a remote area of Afghanistan, where thousands of years of hardscrabble tribal culture increasingly mixes with a resurgent Taliban militancy, this is how Fazl Ahmad allegedly died.

Local officials in Ghor province said one of Ahmad's distant relatives was suspected of killing a former Taliban commander. In December, militants dragged Ahmad from his house and cut out his eyes in retaliation.

Ahmad was still alive and screaming when the attackers began carving the skin off his chest, leaving his heart exposed. Then they threw the 21-year old laborer off a 10-story cliff, officials said.

"They skinned him alive," said Ruqiya Naeel, a member of parliament from the area.

The Taliban denied involvement in the grisly crime, the aftermath of which was documented in a recently circulated video and photograph.

But even so, Ahmad's death is the latest in a string of violent acts across Afghanistan over the past six months. Rattled officials say the 15-year war has taken an increasingly brutal turn.

"The amount of casualties, particularly with civilians, is a crime -- a crime against humanity, a crime against Afghanistan, and a crime against our people," Afghan President Ashraf Ghani said, somberly, in a meeting with reporters last week.

Since 2001, the United States has invested more than $100 billion building Afghan military and police forces, a judicial system and schools in hopes of moving the country closer to normality. But all that spending appears to have done little to slow a cycle of rage and revenge that has made Afghanistan one of the world's most dangerous countries.

Horrific violence is nothing new in Afghanistan.

Public executions were common when the Taliban ruled the country in the 1990s, and tens of thousands of Afghans have been killed during the post-2001 Taliban insurgency. Afghanistan, like neighboring Pakistan, also has a long history of cultural and religious conservatism associated with violent retribution.

But analysts say the scale of the brutality continues to evolve as the Taliban becomes more fragmented and pushes out into additional areas of Afghanistan. Younger Taliban commanders also now operate more independently and are increasingly inspired by other brutal acts easily viewed on the Internet, they say.

Over the past month, after a U.S. drone strike killed Taliban leader Akhtar Mohammad Mansour, militant groups have hijacked at least five buses, dragging passengers into the road to execute dozens of them, especially if they or members of their families were suspected of being police officers or soldiers.

There also have been three recent deadly attacks on Afghan courthouses or judicial employees. Last month in Jowzjan province, a reported Taliban militant armed with an assault rifle shot and killed a burqa-clad woman for alleged adultery, according to a video of the crime posted to YouTube.

"There are now tens of examples of public lashings, executions, and killings," said Abdul Jama Jama, a provincial council member in Ghazni province.

In recent days, the United Nations, Amnesty International and the Afghan Independent Human Rights Commission also have expressed concern over what they view as a hardening culture of violence here.

Brig. Gen. Charles H. Cleveland, chief spokesman for the U.S.-led coalition, said some of the recent reports of violence "looked like the days pre-9/11." But he cautioned that "the base line is pretty high" for sweeping assumptions about whether brutality generally is worsening.

Still, Afghan officials and analysts are worried as the violence also expands into areas of Afghanistan that until recently had remained relatively safe.

A push by the Taliban, dominated by ethnic Pashtuns, into northern and central Afghanistan, where large populations of ethnic Tajiks and Uzbeks reside, has proved especially destabilizing, officials said.

Once the Taliban settles into an area, its fighters often begin aggravating historical rivalries among ethnic groups as well as stoking more-localized feuds that in some cases have simmered for decades. That is another reason for the growing brutality, officials said.

"They are changing their war tactics," said Shah Waliullah Adeeb, a former governor of Badakhshan province. "They are trying to show people that the government is weak . . . and show that they are in charge."

But some analysts say that more fundamental -- and dangerous -- changes within the Taliban may be leading to greater upheaval.

As the original leaders of the insurgency die, they are being replaced by younger commanders who appear less interested in maintaining ties to the local areas in which they are fighting. These fighters also are more connected through the Internet to the global ambitions of militant Islamic groups, which is resulting in some Taliban commanders' attempting to borrow the fear tactics used by the Islamic State in Iraq and Syria.

This month, for example, a group of Taliban fighters killed a high school student in Ghazni province by cutting off his nose and ears after accusing him of being a spy, local officials said.

"The Taliban had always been the village homeboys, but I think that is changing quite dramatically," said Vanda Felbab-Brown, a senior security and intelligence fellow at the Brookings Institution. "But the younger generation is more accepting of violence, less remembering of the horrors of the civil war [of the 1990s], and much more socialized to the global agenda."

Other analysts caution that the recent violence is more a symptom of the broader Afghan culture, where a pattern of revenge and killing has been common and disputes among families or villages often have little to do with the war.

"People want to settle old scores," said Najib Mahmood, a law professor at Kabul University. "You can hardly find any house that does not own a gun because of the war, and people use a gun even for a minor issue."

That historical inability to break the cycle of revenge is one reason that human rights groups and European ambassadors were angered by Ghani's recent decision to resume executions of Taliban figures.

Last month, after a truck bomb killed 64 people in Kabul, the government hanged five Taliban prisoners. Since then, the Taliban has pointed to the executions to justify its attacks on the Afghan judiciary.

Some analysts also worry that President Obama made a mistake in ordering last month's drone strike that killed Mansour, the Taliban commander.

They note that violence in Afghanistan escalated last summer after it was announced that the Taliban's other former leader, Mohammad Omar, had died two years earlier.

They now fear that the trend will accelerate as new Taliban leader Haibatullah Akhundzada seeks to consolidate his power.

Akhundzada is an Islamic cleric and the Taliban's former top judge. But many analysts consider him to be even more rigid than Mansour, who was a former Taliban government minister who witnessed the carnage of Afghanistan's civil war in the 1990s.

"Mansour believed a terrible outcome for Afghanistan would be a protracted civil war in Kabul and the north," Felbab-Brown said. "Many of the younger commanders don't have that restraint."

Akhundzada, in contrast, in the past issued religious edicts authorizing suicide bombings as well as Taliban-on-Taliban executions to deal with dissenters, according to Western intelligence assessments.

"The Taliban under Haibatullah will become even more dangerous," said Rahimullah Yusufzai, a Pakistan-based expert on militancy.

As a result, Kabul University's Mahmood predicted, Afghanistan will continue to slide even further away from "the rule of law."

"It will take decades to see Afghanistan become a normal country again," he said.

Mohammad Sharif and Sayed Salahuddin in Kabul and Aamir Iqbal in Peshawar, Pakistan, contributed to this report.