Islamic State terrorist (file)
Islamic State terrorist (file) Reuters

Islamic State (ISIS) executed a prominent human rights activist in Mosul, Iraq last week, the United Nations (UN) said late Saturday - over one critical Facebook post. 

Samira Salih al-Nuaimi criticized IS's destruction of monotheist and Muslim religious sites in Iraq earlier this month in Facebook comments, after reports surfaced that the terrorist group had destroyed several holy sites, including the tombs of the Biblical Daniel and Jonah

On September 17, terrorists retaliated by abducting al-Nuaimi at her Mosul home, according to the Independent, and tortured her for five days before executing her Monday. 

The lawyer and prominent activist worked for "detainee rights," according to NGO Gulf Centre For Human Rights.

"She used to stand before courts in order to defend those who were detained by U.S. forces, and she did that for free," a Mosul resident told NBC News last week. 

The UN strongly condemned al-Nuaimi's death, which was by firing squad in the city center - in a series of comments over the weekend.

“By torturing and executing a  female human rights lawyer and activist, defending in particular the civil and human rights of her fellow citizens in Mosul, ISIS continues to attest to its infamous nature, combining hatred, nihilism and savagery, as well as its total disregard of human decency,” Nickolay Mladenov, the UN envoy to Iraq, said in a statement.

International media has widely covered the terror group's brutality to women under IS's reign, where women have largely been ordered to cover up completely and stay at home.

A targeted campaign against prominent female activists also appears to have been launched in Iraq, according to the Independent, as at least two more female lawyers have gone missing over the past week from their Mosul-area homes.