Pakistani police opened a hate speech investigation involving two Muslim clerics on Sunday after the killing of a university student over allegations he committed blasphemy.
The clerics are accused of attempting to disrupt the funeral of student Mashal Khan, who was beaten to death by fellow students after a dormitory debate was followed by accusations of blasphemy being spread across a university campus in the northern city of Maradan.
University officials had issued a public notification hours before the murder naming three students being investigated for "blasphemous activities".
Blasphemy is an extremely sensitive topic in Muslim majority Pakistan, where penalties range from small fines to the death sentence, and dozens of people are on death row in the country's jails.
There have been at least 65 recorded cases of vigilante murders since 1990, according to figures from a Center for Research and Security Studies report and local media.
In a statement released to the press on Saturday, Prime Minister Nawaz Sharif said he was "shocked and saddened by the senseless display of mob justice that resulted in the murder of a young student, Mashal Khan, at Wali Khan University".
Mardan police chief Alam Shinwari said 20 people had been identified as culpable in the killing on the basis of videos taken during the attack, and 15 had been arrested. He said they would be tried by anti-terrorism courts.
Police say they are also investigating the clerics in Khan's hometown of Swabi, some 60 kilometers south of Mardan, for attempting to disrupt funeral proceedings and instigate hatred against the dead student's family.
"The two clerics ... [used] the mosque loudspeaker for hate speech against the slain student and his family and ... created hurdles for the people and another cleric to participate in the funeral," a senior Swabi police official told Reuters. He spoke on condition of anonymity for fear of being targeted by religious hardliners.
A local imam had refused to lead the funeral prayers at Khan's funeral on Friday, according to Swabi resident Salman Ahmed. A technician who was asked to do so in the cleric's place was confronted by several people afterwards.
In his press release, the prime minister said the perpetrators of the attack would be brought to justice.
"The nation should stand united to condemn this crime and to promote tolerance and rule of law in society," Sharif said.
However, Pakistan's government has been vocal about blasphemy in recent months, with Sharif issuing an order in March for the removal of content deemed blasphemous online and threatening "strict punishment" for those violating the law.