In an audio recording released on Thursday and shared via an online private messaging platform, Ehsanullah claimed that he along with his family had managed to escape from the custody of Pakistan Army and intelligence agencies on January 11.
Ehsanullah, who became the spokesperson for the breakaway Jamaatul Ahrar faction after the TTP split, had voluntarily turned himself in to the intelligence agencies on February 5, 2017 - and remained in custody even since.
He had shared extremely sensitive and important information while in custody, which led the security forces to smash the local and international networks of the TTP and Jamaatul Ahrar, The Express Tribune quoted informed sources as saying.
Several terrorists from the outlawed groups were arrested based on his leads, they added.
But Ehsanullah escaped during one such operation against terrorists, the sources said, adding that "some operations are still under way based on the information" shared by the former TTP spokesman.
The development came a day after netizens on Friday set off a storm of speculation about the audio recording initially posted on Facebook and then shared on other social networking sites in which he claimed to have escaped, The Express Tribune reported.
The authenticity of the clip has yet to be verified, though the voice appears to be similar to that of Ehsanullah's.
There has been no official word on the audio clip or the alleged escape.
Ehsanullah is responsible for several terror attacks in Pakistan and had a bounty of $ 1 million on him. In 2012, he was involved in the attack on Malala, when she was shot in the head for defying Taliban diktats and pursuing her education, while highlighting the atrocities of the militant outfit.
He is also a prime accused in the 2014 attack on the Army Public School (APS) in Peshawar which killed 134 school children and 15 staff members.
Ehsanullah was involved in the suicide bombing of Shiites in Rawalpindi and Karachi, killing of nine foreign tourists and their guide in Gilgit-Baltistan area, twin blasts targeting peace committee volunteers in Mohmand agency, suicide attack near the Wagah border and the 2016 bombing of an Easter gathering in a Lahore park that killed at least 75 people and injured more than 300 others.