A local guard force member who worked at the U.S. Embassy in Sudan died while in the custody of the Rapid Support Forces paramilitary group, the U.S. Bureau of African Affairs said.
Tarig Hassan Ahmed, the guard, who worked at the embassy in Khartoum, was described as a "dedicated" and "respected" colleague and friend to many in embassy community. The U.S. said it was "deeply saddened and disturbed" by Ahmed's killing.
"We have asked the RSF to provide full details of the circumstances surrounding Mr. Hassan Ahmed's detention and death and to ensure those responsible are held accountable," the bureau said in a statement.
ABC News has asked the RSF for comment on the incident.
The death came just a few weeks after the RSF agreed to a code of conduct at U.S.-mediated talks in Geneva, with the paramilitary group committing to enforcing new conduct for its fighters that includes a command directive for its fighters to comply with Jeddah Declaration commitments and international humanitarian law as well as refrain from violence against women.
"These new commitments must be reflected in the actions of RSF troops on the ground, who have committed ethnic cleansing and crimes against humanity since the outbreak of war against Sudanese civilians," said U.S. Secretary of State Antony Blinken.
A new report released by the United Nation's Independent International Fact-Finding Mission for Sudan found that warring parties have "committed an appalling range of harrowing human rights violations and international crimes," including many that may amount to war crimes or crimes against humanity.
It is the first report by the independent fact-finding mission, Mohamed Chande Othman, the mission's chair, said the "gravity" of its findings "underscores the urgent and immediate" action needed to protect civilians.
New visual evidence obtained by Lighthouse Reports has also found RSF and allied militias implicated in extrajudicial killings of unarmed civilians, including ethnic massacres that took place in the Western region of Sudan's Darfur.
Meanwhile the war in Sudan continues, with fighting now ongoing in over 70% of the Northeast African nation's states. At least 38 people were killed and 116 injured following what local groups say were "indiscriminate artillery and air strikes" by the RSF in Sudan's Sennar state, Emergency Lawyers, a monitor for civilian casualties and humanitarian violations said in a statement.
The conflict has killed at least 20,000 people as it enters its seventh month, U.N. officials say. Local groups however warn the true toll is likely much higher.
"Much more needs to be done, of course; we're mindful of that," said White House national security adviser John Kirby at a White House press briefing last week. "The RSF and the SAF need to uphold their commitments."