GENEVA (AP) — A U.N. panel began grilling American officials Wednesday over the country’s compliance with a key anti-torture treaty, raising a series of alleged violations and admitted “lapses” since the 9/11 attacks.

At the start of a two-day hearing, Alessio Bruni of Italy, one of the panel’s chief investigators, told the high-level U.S. delegation that it must answer for alleged violations ranging from CIA rendition at so-called black sites to police brutality and Guantanamo Bay conditions. He asked what concrete measures have been taken to implement President Barack Obama’s “clear” directives against torture.

A day earlier, the committee took private testimony from death penalty experts, anti-torture activists, former Guantanamo Bay detainee Murat Kurnaz and the parents of Michael Brown, the victim in the Ferguson, Missouri shooting case that has riveted a nation. A decision is expected later this month about whether Ferguson Officer Darren Wilson, who is white, will face criminal charges for fatally shooting Brown, 18, who was black and unarmed.

Former detainee Kurnaz and Brown’s father, Michael Brown Sr., were scheduled to speak to reporters at the United Nations in Geneva later Wednesday.

The U.N. Committee Against Torture, which has 10 independent experts, is responsible for reviewing the records of all 156 U.N. member countries that have ratified the U.N. Convention Against Torture, which also prohibits all “cruel, inhuman or degrading treatment or punishment.”

Mary McLeod, the State Department’s acting legal adviser, conceded the U.S. record since the 9/11 attacks “did not always live up to our own values,” including those it is obliged to uphold under the treaty, which took effect in 1987. The United States signed on to the treaty in 1988 and ratified it in 1994.

“As President Obama has acknowledged, we crossed the line and we take responsibility for that,” she said. “The United States has taken important steps to ensure adherence to its legal obligations.”

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