PESHAWAR: The Tehreek-i-Taliban Geedar group commander who claimed the deadly attack on Bacha Khan University in Khyber Pakhtunkhwa's Charsadda Wednesday is Umar Mansoor, the de facto operational head of TTP in KP.

Journalist Hasan Abdullah tells Dawn.com Mansoor is the faction's commander specifically in Charsadda, Darra Adam Khel, Noshera and surrounding areas. "He had been very close to Hakimullah Mehsud's inner circle and was also close to Umar Khalid Khorasani at one time," says Abdullah.

He adds while he is said to have shifted to Afghanistan after Pakistan's military operation in 2014, Mansoor is reported to have crossed into Pakistan at several points.

A Reuters profile titled 'Pakistan's most hated man: volleyball player, child killer' described Mansoor as a 37-year-old father of three and volleyball enthusiast who is nicknamed "Slim".

His real name is Umar Mansoor and is also claimed by TTP to be the mastermind of 2014's massacre of 132 children and nine staff at a military-run school in Peshawar - the deadliest militant attack in Pakistan's history.

A video posted on a Taliban wesbite after the Army Public School attack showed a man with a chest-length beard, who sought to justify the Dec. 16 attack. The caption identified him as Umar Mansoor.

The Taliban said the APS attack, in which gunmen wearing suicide-bomb vests executed children, was retaliation for a military offensive carried out by the Pakistani army.

Six Pakistani Taliban interviewed by Reuters confirmed the mastermind was Mansoor. Four of them said he is close to Mullah Fazlullah, the embattled leader of the TTP who ordered assassins to kill schoolgirl activist Malala Yousafzai.

Mansoor got a high school education in the capital, Islamabad, two Taliban members said, and later studied in a madrassah.

Mansoor has two brothers and spent some time working in the city of Karachi as a labourer before joining the Taliban soon after it was formed, in late 2007, said one commander.

His nickname is "naray," a word in the Pashto language meaning "slim", and he is the father of two daughters and a son, said another commanders.

The Taliban video describes him as the "amir", or leader, of Peshawar and nearby Darra Adam Khel. Mansoor deeply opposes talks with the government, the commanders said.

"He was very strict from the start when he joined," a commander said. "He left many commanders behind if they had a soft corner (of their heart) for the government."

2011-15: Attacks on educational institutions in Pakistan