Alongside many others here I also feel that the TTP did not kill him. Regardless of the Asia Times article which seems speculative at best, I feel that since there's no love loss between the TTP and the Army, there is no need for the TTP to masquerade under a pseudonym, especially something called the Asian Tigers which sounds like a IPL cricket team. The TTP could eat kittens, it's not going to dent their reputation any further, so if they did it - They'd tell you they did it. That's what i think.
Similarly, Col. Imam has openly expressed to The Times, CNN, BBC his views and listed his experiences with militants. I can only imagine someone of his stature, being the mentor of Mullah Omar would galvanize respect and would instantly be known as a war hero in places like FATA, so it puzzles me that any militant would dare to take him hostage, especially under the strict code of pashtunwali. So why would this group ask for Mullah Baradar and Kabir as a prisoner exchange? It would be like asking a captured Osama for a futgitive Zawahiri.
Doesn't make sense.
It must be noted that in places such as north Waziristan, we have to remember that there's also PRO-government tribes, militants who has been known to carry out summary executions etc. One instance of this was the murder of a very brave journalist working for PBS frontline called Hayat Ullah Khan. On June 16, 2006, Hayat Ullah Khan's body was found in North Waziristan tribal region. He had disappeared in December 2005 after reporting that an alleged Al Qaeda member had been killed by a U.S. missile, not in a bomb-making accident as was claimed by Pakistan. He broke the first story of drones being used in Pakistan. Subsequently he was later found dead in a ditch, tied in government made-handcuffs as reported by PBS Frontline.
Am I saying that the GoP killed Khwaja? Of course not. But to rule anyone out, and to instantly pin this on the TTP is bad journalism and is evident that a lot of people here are pushing an agenda. If anything, he could have been captured by thugs/bandits of which many have become ubiquitous in areas such in north due to the deteriorating security condition.
I do honestly believe that these two were sincerely making a documentary, what convinces me is that both Khawaja and Col. Imam had been given alot of media attention in the last 18 months and that a reputable broadcaster picked up on this. Also the journalist they dispatched was credible and experienced and obviously in this case very naive.
Lastly, RIP.