BAGHDAD — The assassination of an outspoken Iraqi researcher who had antagonized the Islamic State as well as Iraq’s Shiite militias was seen Tuesday as a message to the Iraqi government, but it was unclear who killed him.
The researcher, Hisham al-Hashimi, 47, was a prominent figure and a favorite of television news channels, which turned to him for his unvarnished takes on Iraq’s lack of security and the government’s difficulties confronting both Sunni Muslim and Shiite Muslim extremists.
He was killed in front of his Baghdad home at dusk on Monday by two gunmen on motorcycles, who have not been caught or identified.
No group claimed responsibility for his assassination, which shocked Iraqis and dominated the television news in Iraq on Tuesday. Young people who supported his views of the militias took to the streets in grief and anger.
Security analysts pointed out that he had enemies both among the Sunni extremists in the Islamic State and in the Shiite militias, some of which are close to Iran. Mr. al-Hashimi also antagonized some politicians and government figures, especially in the previous government, by accusing them of failing to confront the militias that were shooting protesters during antigovernment demonstrations last fall.
Analysts both inside and outside Iraq read his killing as a worrying sign for the government and a flagrant challenge to its declared effort to institute the rule of law.
Prime Minister Mustafa al-Kadhimi, who took office in May, has made it a priority to rein in the Shiite militias, and his government carried out a raid on one of them, Khataib Hezbollah, last month.
Khataib Hezbollah is close to Iran and has been accused by the United States of conducting attacks that have killed three Western soldiers and a civilian contractor.
Mr. al-Hashimi praised the raid, and has long goaded the government to stand up to the militias. Consequently, there was widespread suspicion that Khataib Hezbollah or an allied militia was responsible for his killing.
However, Mr. al-Hashimi also irked the Islamic State, which has referred to him in statements as “the liar of Baghdad.”
In recent weeks he told his brother that he had received a serious threat from the Islamic State, and he told friends he had been threatened by militias.
Whichever group or figure ordered his killing was sending a message to the government, said security analysts and politicians.
“This was all about Kadhimi,” said Michael Knights, a security analyst at the Washington Institute for Near East Policy, adding that Mr. al-Hashimi was “close to the Kadhimi circle.”
Mr. Hashimi’s stinging critiques of the militias were not new, he said. What has changed recently was Mr. al-Kadhimi’s accession to power.
Mr. al-Kadhimi said Tuesday that no one was “above the law” and that his government would hunt down the killers. He ordered an investigation headed by the deputy interior minister and said a street would be named after Mr. al-Hashimi.
President Barham Salih said in a statement late Monday that “the assassination of the honest, patriotic, decent researcher Hisham al-Hashimi by outlaws is a vile crime that targets an Iraqi and his human right to live a free and decent life.”
Mr. al-Hashimi was killed as he parked in front of his house in the middle-class Zaiouna neighborhood of Baghdad. One of the gunmen ran up to his car and, using a silencer, shot him at point-blank range. At least one of the four bullets entered the back of his neck.
The two men escaped as neighbors and three of Mr. al-Hashimi’s four children helped pull his body from the car. He was taken to a hospital and died soon after.
Mr. al-Hashimi, who was originally from Nasiriya in the south of Iraq, had been part of the opposition against Saddam Hussein and was imprisoned by him. When he was released in 2002, he turned to journalism, and when Al Qaeda in Mesopotamia emerged soon after, he started analyzing security incidents and gathering data. He had his own website and security center and had recently published papers related to the Iraqi militias.
Most unnerving for longtime observers of Iraqi politics was the fact that the killing happened in the open and that the killers appeared to have easily escaped.
“This is the biggest indication that there’s no state,’” said Izzat al-Shabandar, a longtime Iraqi politician, who is close to the security forces and a longtime opponent of the presence of foreign forces in Iraq. The Iranian-backed militias, the Islamic State and the American forces in Iraq, he said, were “all stronger than the state.”
Falih Hassan contributed reporting.