 -- The Baghdad bureau chief for the Reuters news agency was forced to leave Iraq over the weekend after militias threatened his life for reporting that an ISIS suspect in custody had been murdered in Tikrit recently by Iraqi national police, according to the newswire and informed sources.

Ned Parker, an American journalist who leads Reuters' coverage in Iraq, safely departed the country after his name and photo were broadcast and posted online by individuals affiliated with Shi'a militias who demanded he be expelled from Iraq or killed, the news agency and friends of the journalist said.

Last week, Reuters correspondents were present when an ISIS suspect in custody in Saddam Hussein's hometown Tikrit was hacked to death by a mob of Iraqi national policemen shouting that they were avenging a colonel killed by ISIS, the Sunni-Muslim terror group that controls large swaths of western and northern Iraq. Tikrit, a Sunni town north of Baghdad, was recently reclaimed from ISIS by security forces with help from U.S. airstrikes.

"This is only the latest in a long string of troubling tripwires that signal the rebirth of the 'Republic of Fear' and Iraq's slide toward the abyss," said Ali Khedery, who was an adviser in Baghdad to five U.S. ambassadors, of the threats to Parker. "One of the most important tenants of a police state is to silence dissent and deny access to international observers critical of the government in order to facilitate unchecked pogroms. This is all part of a concerted campaign."

The blatant killing of a prisoner in front of the journalists was one of the most alarming examples of the types of war crimes committed with apparent impunity by Iraqi Security Forces and uncovered in a six-month ABC News investigation that aired in March on "World News Tonight With David Muir." It also comes on the eve of Iraqi Prime Minister Haider al-Abadi's White House huddle with President Obama on Tuesday.



[A bound and blindfolded detainee appears to be dropped – or possibly hung from the neck according to one analyst -- from what looks like an Iraqi military base guard tower. The image was posted on Instagram.]

Dozens of gruesome photos and horrifying videos were found to have circulated within the dark underbelly of Iraqi social media -- Instagram, Facebook and Twitter -- since last summer but remained secret to most until exposed by ABC News on March 11. The imagery showed men who appeared to be wearing the uniforms and insignia of Iraq's U.S.-created and U.S.-armed Ground Forces Command, Special Forces, SWAT special police and counter-terrorism teams from the Interior Ministry's Emergency Response Brigade proudly committing the same types of atrocities as ISIS: beheadings, torture, roadside executions and bodies dragged behind trucks.

The Iraqi government's military spokesman, Gen. Saad Maan, has said there will be an investigation of the extrajudicial killing of the ISIS prisoner witnessed by the Reuters correspondents. Last month in an on-camera interview, Maan told ABC News that the social media imagery depicting war crimes also would be probed, too, though four weeks later Maan is still promising an "update" sometime in the future.

In the ABC News reports last month, the Pentagon revealed for the first time that "certain units" of the Iraqi Security Forces had been denied U.S. military aid and weapons under the federal "Leahy Law" because of "credible information" of past human rights abuses. The law's author, Sen. Patrick Leahy, D-Vermont, said Congress should put the brakes on a $1.5 billion military aid package approved in December, which experts say is likely delivering 50,000 light infantry weapons into the hands of the Iraqi Security Forces and affiliated Shi'a militias with questionable vetting for human rights violations.

"There is very little end-use monitoring of the weapons" shipments to the Baghdad government, said one of several U.S. officials who told ABC News they remain highly critical of the arms gifts to Iraq. For one thing, security in Iraq restricts travel by U.S. military members who are tasked with the nearly impossible task of tracking shipments such as the 43,000 M4 rifles Congress approved last year to create seven new Iraqi brigades, officials admit.

The U.S. State Department finished its annual Country Reports on Human Rights, which includes Iraq, in February, according to officials, but its public release has been delayed.

Since the ABC News reports a month ago, video and photos depicting horrors of the kind generally associated with imagery produced by the ISIS propaganda teams have continued to circulate online. Much of it is attributed to the brutal Shi'a militias, whose numbers Khedery said dwarf the government's forces.

U.S. airstrikes only assisted the Iraqi final push to reclaim Tikrit under the condition that most of the Shi'a militias pull back from the town so they would not directly benefit from American military might.

And yet Gen. Fadhil al-Barwari, commander of Iraqi Special Forces -- the primary remaining government counterterrorism unit -- staged a photo opportunity the day Tikrit was liberated from ISIS with one of the most celebrated militia commanders, Abu Azrael, the fabled "Angel of Death."

According to Iraqi news reports, Abu Azrael went from college professor to weigh-lifting Shi'a militia hero brandishing an American M4 rifle -- and now an Iraqi Special Forces cap, scarf and patches given by Barwari.