Who killed the PTM activist Usman Kakar, and why?

 On 17 June 2021, Usman Kakar was admitted to a private hospital in Quetta.
PKMAP's head Mahmood Khan Achakzai had informed that Usman Kakar suffered a massive stroke and had serious injuries. Bilawal Bhutto then advised that for better treatment Usman Kakar should be taken from Quetta to Karachi. After mutual consent, Usman Kakar was admitted from Quetta to Agha Khan hospital in Karachi.

After staying there for a few days, he lost his life.
Yousuf Khan Kakar, the province head of PKMAP, who also happens to be a close relative of Usman Kakar, revealed shocking things in an interview to BBC.

Yousuf Khan Kakar says
“On 17 June 2021, Usman Kakar was present at PKMAP's Jinnah Road office at 3 pm, after which he left for his home with a security guard.
 The security guard dropped him at his house and came back to the office, the guard also told that when he went there, his 11-year-old daughter and a woman were present. That woman and daughter were on the first floor.
Usman Kakar told me to go back and I came to the office.
Yousuf Khan Kakar further told that while he was going to rest in his room, some people reached there and attacked Usman Kakar. Shortly after that, as soon as his family came to know, they admitted Usman Kakar to the hospital. Usman Kakar was badly injured in this attack.”

Yousuf Khan Kakar claimed that he had not suffered any brain haemorrhage nor had he suffered any stroke. He also told that we did not speak that time because we wanted Usman Kakar himself to tell everyone about what happened to him and who had attacked him.
In the official letter issued by his party, he was given the status of a martyr, which clearly shows that the party also understands that Usman Kakar's death was not ordinary.
Shortly before this incident, Usman Kakar had said in the senate that pressure is being made on us to stop talking about ISI and Army or else the consequences could be lethal. If anything happens to me or my family, then Pakistan's intelligence agency will be held responsible for it.
So all these things show that Pakistan's intelligence has put a false post mortem report in front of the world and killed another Pashtun on the ground.