Baghdad (CNN) -- Rights groups called the death of a prominent Iraqi journalist "suspicious" and "politically motivated" Friday, and insisted that authorities conduct a full investigation into his death.
Hadi al-Mehdi had criticized the Iraqi government and used his Facebook account to call for demonstrations. He was shot dead Thursday evening, a senior official with Iraq's Interior Ministry told CNN.
Al-Mehdi was inside his apartment on Abu Nawas street in central Baghdad when gunmen shot him twice with silencer-equipped pistols, said the ministry official, who did not want to be identified because he is not authorized to speak to media.
In a statement released Friday, Human Rights Watch suggested the killing was deliberate. The group says witnesses told them there was no evidence of struggle or theft. Al-Mehdi's cell phone, laptop and other valuables were in the house when authorities arrived, according to Human Rights Watch.
Reporters Without Borders said "there can be no doubt that his murder was politically motivated."
Al-Mehdi's killing "sadly highlights that journalism in Iraq remains a deadly profession," said Joe Stork, deputy Middle East director at Human Rights Watch. "After more than six years of democratic rule, Iraqis who publicly express their views still do so at great peril."
Al-Mehdi had criticized the performance of the government in a popular talk show program called "To Whoever Listens" on a Dimozi radio channel. He also used his Facebook account to call for demonstrations every Friday in Baghdad's Tahrir Square.
Every Friday, since early February, tens of thousands of protesters have participated in demonstrations across the country, apparently inspired by popular uprisings in Egypt and Tunisia. They speak against corruption, restrictions on freedom of expression, unemployment and poor government services. At least 20 Iraqis have been killed and hundreds have been wounded in these protests.
Also in the past months, dozens of activists were arrested by Iraqi security forces; many were released.
Hana Adwar, a prominent Iraqi human rights activist, told CNN that al-Mehdi was one of four journalists picked up by Iraqi army troops at a restaurant on February 25 after the journalists left Tahrir Square, where they had participated in an anti-government demonstration.
He was tortured while in custody and was released few days later after he signed a statement stating that he had not been tortured, Adwar said.
Since then, al-Mehdi had said he received threats. Within the past few days, he posted on his Facebook page that he feared something could happen to him, according to Reporters Without Borders and witnesses.
According to the Journalistic Freedoms Observatory, an Iraqi media watchdog group, 258 journalists have been killed in Iraq since the U.S.-led invasion in 2003, including 191 journalists killed by gunmen and militiamen.