LEFT: About 300 protestors rallied in Baghdad’s Tahrir Square Friday morning, mourning the death of journalist and activist Hadi al-Mahdi. Human rights activist Fadwa Kamal, right, holds a photo of Mahdi. (Annie Gowen)

Radio talk show host Hadi al-Mahdi had already been detained and beaten for his outspoken criticism of Iraq’s government.

This week, as Mahdi threw himself into preparing for a protest scheduled for Friday in Baghdad’s Tahrir Square, the intimidation escalated.

“I have lived the last three days in a state of terror,” he wrote in a post on his Facebook page Thursday morning. “There are some who call me and warn me of raids and arrests of protesters. There is someone saying that the government will do this and that. There is someone with a fake name coming on to Facebook to threaten me.”

Hours later, Mahdi was found dead in his home, with two gunshot wounds to the head.

It was unclear Friday who had killed Mahdi or why. But his death sparked fears among journalists and activists that as U.S. troops leave the country, Iraq’s ruling class is turning to some chillingly familiar tactics to silence dissent.

Despite the constitutionally enshrined right to free speech that came following the overthrow of longtime dictator Saddam Hussein, threats and violence toward those who publicly challenge the government of Prime Minister Nouri al-Maliki appear to be on the rise.

“I think Iraq is at a crossroads, with the Americans leaving,” said Samer Muscati, director of Iraq research for Human Rights Watch. “The signs of authoritarianism are quite disturbing.”

Maliki’s government had no comment on Mahdi’s death and has denied intimidating dissenters. But the primary opposition group in parliament, Iraqiya, on Friday demanded a full investigation into the killing. The bloc, led by former prime minister Ayad Allawi, condemned the crime as a “desperate attempt at muzzling and to bring Iraq back to the republic of repression, fear and despotism.”

A spokesman for the government’s Baghdad Operations Command said Mahdi’s death was a “regular criminal case” and would be investigated by police.

The small community of Iraqi journalists and activists in and around Baghdad grieved Mahdi’s death Friday — and were chilled with fear. Mahdi is the seventh journalist to be killed in Iraq this year.

“We all feel we may have the same end — like Hadi,” said Dhikra Sarsam, a local journalist and a friend of the slain talk show host.

On his radio program, “To Whoever Listens,” Mahdi, 45, had loudly criticized Iraqi politicians of every stripe, including Maliki and Allawi. Mahdi had a flair for the dramatic and often used humor to poke fun at local leaders and their corrupt ways. Maliki loyalists had often complained about Mahdi’s views to the radio station that aired the thrice-weekly program, supporters said.

When the spirit of the Arab Spring swept the country in February, Mahdi was front and center. In an interview with The Washington Post that month, Mahdi described how, after a demonstration suppressed with violence that left more than 13 people dead, he was among four journalists picked up by security forces and driven to the headquarters of the Iraqi Army’s 11th Division. He said he was beaten, given electric shocks and threatened with rape before being asked to sign a statement saying he had not been tortured.

After that, the threats began.

“He would always tell me about different threats. Phone calls, letters, e-mails, but he never acted fearful. He just kept speaking out,” said Rebecca O’Farrell, a friend of Mahdi’s and an activist. “I’d tell him to shut up, just stay out of sight for a while, but he’d always tell me he was okay and not to worry.”

In June, Mahdi sent O’Farrell an e-mail that began, “Iraq’s new dictator wants to kill me with knives!” He believed Maliki had assigned mercenaries to stab him on the street, he told her.

Nonetheless, Mahdi had continued to attend protests each Friday this summer at Tahrir Square, even though attendance dwindled with each passing week. Those who showed up said they were often harassed by government forces.

About two months ago, Mahdi quit doing his radio show out of fear for his safety, friends said. Even as his apprehension grew, however, Mahdi remained committed to attending Friday’s scheduled protest to push for government reform. Organizers were hoping for fresh energy and new momentum after a slowdown during the Muslim holy month of Ramadan.

“I will take part in the demonstrations, for I am one of its supporters,” he wrote Thursday on Facebook.“I firmly believe that the political process embodies a national, economic, and political failure. It deserves to change, and we deserve a better government. In short, I do not represent any political party or any other side, but rather the miserable reality in which we live.”

Mahdi stayed on Facebook until 2:30 p.m., friends believe, until he was summoned to the door of the small house just off Abu Nawas street in Baghdad. He let in his guest, or guests, then went to the kitchen to pour glasses of water. An attacker followed him, pulled out a small handgun and lodged two bullets in his skull. He was still holding the water jug when he fell.

“He always said he was on the list for assassination,” said Ammar al-Shahbander, a friend who is the Iraq chief of mission for the Institute for War and Peace Reporting. “I personally didn’t think it would happen. But Hadi was so sure about it.”

The demonstration that Mahdi had called for Friday turned into a wake of sorts, as about 350 protesters gathered in the sun-filled square. Some held up a large picture of Mahdi edged in black; others held banners inscribed with his last Facebook post. They sang and chanted that his blood would not be spilled in vain.

Alwan is a special correspondent. Staff writer Stephanie McCrummen in Washington contributed to this report.