He is known simply as the "Butcher of Kabul" and, after 20 years in self-imposed exile, Gulbuddin Hekmatyar returned last week to the Afghan capitol he once mercilessly massacred. President Ghani and members of his national unity government warmly welcomed the warlord.

After fighting the Soviet Union and the Afghan communist government during the 1980s with his Hezb-e-Islami militia, Hekmatyar, 69, and other warlords eventually sparked civil war within Afghanistan. To assuage his radicalism, he was elevated to prime minister in 1993. But that was not enough; shortly after that he was accused of orchestrating the destruction of Kabul and the deaths of tens of thousands of civilians and coalition government soldiers.

"He is not a peaceful man. Giving him power will only increase the number of extremists around him," Mullah Paiman Pirzadeh, a Kunduz member of Parliament who is a former confidante and supporter of Hekmatyar, told Fox News. "When I was with him, I was stupid and he was stupid. Luckily I found myself and changed my mind."

Butcher (on right)

Gulbuddin Hekmatyar (right) (Hollie McKay/Fox News)

Yet following months of negotiations between the Afghan Peace Council and the Hezb-e-Islami delegation last year, Hekmatyar in September signed a peace deal with the government allowing him to emerge a few weeks ago from the mountains of neighboring countries, have his name wiped from the United Nation's sanctions list and take a legitimate place in the government as leader of the Hezb-e-Islami political party. But the most significant of Hekmatyar's conditions in signing was that the 3,000-plus Hezb-e-Islami members in prison be released immediately.

Hekmatyar has publicly claimed that his main goal now is to "end this war and rescue the country from crisis," and he has pledged that his people will eschew violence.

But for the millions who lost loved ones, his words are empty and his flamboyant return adds to the already volatile security situation.

The immunity awarded to Hekmatyar -- without any accountability for his many terrorist attacks and war crimes, which are believed to be more numerous than those of any other faction leader -- has left many Afghans feeling angry and betrayed. Driving through the streets of Kabul, posters of him put up by supporters have been defaced and families who lost loved ones to his warfare have launched public protests.

Locals told Fox News of their haunting memories of him planting land mines on the outskirts of the city and the constant shelling. In one day alone he ordered the indiscriminate launching of 1,600 rockets to destroy the city and those rallying against him.

His followers have been accused of mass torture of intellectuals, throwing acid on outspoken women and operating extreme torture cells in Pakistan.

Despite the opposition, over the past week the process of releasing Hezb-e-Islami prisoners, mostly held in the infamous Pul-e-Charki and Bagram jails began, according to terms of the deal. The first batch of prisoners to be released includes more than 70 inmates. Hezb-e-Islami leadership also has mandated that its members will not hand in their weapons, saying they must be armed for their own security.

Butcher billboard

Defaced billboard of Gulbuddin Hekmatyar (Hollie McKay/Fox News)

The problem, locals said, is that there are no mechanisms to track inmates after they are released to determine if they are returning to terrorist activity and gauge how radicalized they may have become behind bars. Those jailed are said not to be political prisoners, but were captured while waging direct acts of war.

"The prisoners are associated with crimes; they were either arrested in the battlefield or while committing other crimes such as planting mines and improvised explosive devices, suicide attacks and regular assaults on Afghan and international forces," noted Hashim Watdatyar, a former Afghan spokesperson for the U.N. Office of Drugs and Crime. "Once they are released, they will not be tracked and, like other warlords, criminals and Mafia within the system, they also will either work with government or will be associated with the politicians as their militias, bodyguards or parliamentarians."

Aziz Amin Ahmadzai, a prominent Afghan political analyst, concurred that "the prisoners were involved in various crimes, especially insurgency," and captured on the battlefield within the past 15 years. He remains confident that the government "will keep an eye on the prisoners," but emphasized that it as important for Hezb-e-Islami to ensure its members don't pose a danger to society.

And given Hekmatyar's deeply controversial nature, any travel he makes involves hundreds of his own armed militia -- paid for by the government – and that too is causing concern. It is also unknown how many and what kind of weapons the group still has in its arsenal.

"He committed immense terror activity in Kabul, and he even took responsibility for that," former Afghan Vice President Ahmed Zia Massoud said. "Now he has hundreds of bodyguards, and we don't know who these people are. Furthermore, many of the groups aligned with him are the ones fighting our troops. How is that peace?"

Throughout Operation Enduring Freedom, Americans, too, came under Hezb-e-Islami attacks. In 2013, 15 people -- including six Americans -- were killed by a Hezb-orchestrated suicide attack. Following the death of Usama bin Laden in 2011, Hekmatyar called the Americans "barbarians" and praised the former Al Qaeda leader as a "role model for sacrifice and freedom." He issued a direct threat against U.S. Lt. Gen. Karl Eikenberry, the commander of the Combined Forces Command in Afghanistan, saying, "I would like to kill you myself."

Two Hezb-e-Islami commanders remain wanted on the U.S Rewards for Justice program. Washington is offering $2 million for explosives expert Abdullah Nowbahar for a 2012 suicide attack on a Kabul bus carrying foreign airport staff, which killed more than a dozen. They are also offering $3 million for Abdul Saboor, who is said to have orchestrated the 2013 attack that killed American soldiers.

Butcher on windshield

Supporters of Gulbuddin Hekmatyar display his image on their vehicles (Hollie McKay/Fox News)

However, the U.S. has thrown its full support behind the Afghan government's quest to integrate Hekmatyar and his team, signaling that diplomatic agreements are a fundamental way forward in the conflict-ravaged country.

"The United States welcomes the Government of National Unity’s steps to fulfill its obligations in implementing the peace agreement it signed with the representatives of Hizb-e-Islami Gulbuddin (HIG)," the U.S. Embassy in Kabul said in a written statement. "We consider this step clear evidence of the Afghan government’s commitment to restoring peace and stability in Afghanistan, which will ultimately benefit the Afghan people. It is evident that Afghans overwhelmingly yearn for peace, and this agreement will provide an opportunity to bring Afghans together and ensure the safety and security of all sides."

Indeed, over the past month Hekmatyar has called on his Taliban "brothers" to also lay down their arms. But Pirzadeh, the member of Parliament, stressed that such statements are merely tactical endeavors to "make the Americans happy" and create a sense that he is on the side of the good.

Pentagon officials are currently examining plans to bring several thousand more troops to Afghanistan, not simply to assist the struggling Afghan forces but seemingly to pressure the Taliban to enter into a peace agreement.

Yet Taliban leaders have pledged that they will not take part in peace talks unless the Afghan government removes all foreign troops and releases all of its many thousands of prisoners as well.

Nonetheless, Hamid Azizi -- a spokesperson for Hekmatyar who previously worked at the Afghanistan Embassy in Tehran -- insisted that two decades later, his party and its leader have turned over a new leaf and he is certain Hekmatyar will pave the way for other groups to follow suit.

"We are not seeing non-Muslims as our enemies. We respect humanity and human rights," he said. "The conflict of the past destroyed Afghanistan and all parties in the conflict are guilty. We have taken responsibility for our part. But it is time for a new chapter; we should forget the past."

Others, too, see it as a step in the right direction and that all terror groups -- irrespective of name -- should be negotiated with and folded legitimately into the government.

"We have to make it work," former President Hamid Karzai told Fox News. "Any group that renounces violence should be brought into a deal."