Mullah Akhtar Mansour
Two bombers attacked buses carrying police cadets on their way to the capital on Thursday, killing 27 people and wounding dozens more on the western outskirts of Kabul.
"I appeal to the civilized world, including all those human rights bodies, to investigate the brutal murder of my brother and compensate his children" the brother of the late taxi driver Mohamad Azam said.
The Taliban's leadership council chose former deputy Haibatullah Akhundzada as the new head of the group on Wednesday, replacing Mullah Akhtar Mansour just days after he was killed.
The Taliban has not issued a statement to confirm or deny that Mullah Akhtar Mansour is dead, but Afghan officials said the US attack was successful.
The Pentagon said an airstrike in a remote area of the Afghanistan-Pakistan border region targeted Mullah Akhtar Mansour, but his death has not been confirmed.
Talks brokered by Afghanistan, Pakistan, China, and the US were expected to begin in early March, but the Taliban issued a statement saying it would not participate.
Attacks by Afghan troops on foreign soldiers have long been a major problem, but have declined in recent years. Wednesday's killings mark the first such attack since the Taliban's bitter leadership battle.
Mullah Muhammad Akhtar Mansoor dismisses reports of a peace process as "propaganda" and calls for unity among the Taliban, even as some of the group’s highest-ranking members dispute his ascension.
Further discussions will be held after the Muslim holy month of Ramadan. Worries over the Islamic State's expanding influence could be driving the Taliban to negotiate with the government.