Outrage spread across Iraq on Wednesday after the tomb of prominent scholar Husham Al Hashimi was vandalised.
Two gunmen on a motorbike shot Al Hashimi dead outside his home in Baghdad in July 2020 in front of his family. The culprits have never been found.
He is buried in Wadi Al Salam cemetery in the southern city of Najaf.
Pictures circulated on social media showed the damage to Al Hashimi's tomb, which had been graffitied and a cross placed on top of his photograph.
The grave was later cleaned, videos on social media showed.
“The ideas of the martyr Husham Al Hashimi have terrified the cells of darkness, violence and terrorism even after his assassination,” tweeted political analyst Shaho Kurdy.
“These actions are very normal for murderers and organised gangs who love destruction and murder.”
Michael Knights, an Iraq expert at the Washington Institute for Near East policy, said Al Hashimi will “have his revenge”.
Another Twitter user, Ali Al Khafji, founder of a group focused on ending impunity in Iraq, said: “We don’t need revenge, we need justice! Impunity is flourishing in Iraq.”
He added that he “has never seen people like this before”.
Al Hashimi had close contact with diplomats, government officials and other authorities.
It has been reported that his work led to him receiving death threats.
During his funeral, his brother told the public that “shortly before the assassination, he told the family about the death threats [ISIS] had made”.
His family and friends advised him to leave the capital but he vowed to continue his work.
Al Hashimi's research focused on Sunni extremism and he wrote several books on the subject.
In 2014, when ISIS fighters gained control of large parts of Iraq, he advised the government on how to defeat them and spoke frequently to international news outlets.
Departing Prime Minister Mustafa Al Kadhimi blamed groups “outside the law” for the killing.
“We vow to his killers that we will pursue them so they are justly punished. We will not allow assassinations to return to Iraq for a single second,” he said in a statement.
Several people were arrested in connection to the murder but no one has been formally charged nor a court session convened.
During the past two years, Iraq has suffered a wave of assassinations.
Prominent activist Ihab Al Wazni was killed in the central city of Karbala in May 2021 by unknown gunmen.
Many activists and journalists have openly said they fear for their lives and safety because of the increase in targeted killings and feel the government is incapable of protecting them.