On Sunday, Aug. 8 at 6 p.m. NBC Nightly News will air a segment by Kate Snow about Conviction Integrity Units in the United States.

FILE - "NBC Nightly News" anchor Tom Brokaw delivers his closing remarks during his final broadcast, in New York on Dec. 1, 2004. Brokaw says he is retiring from NBC News after working at the network for 55 years. (AP Photo/Richard Drew, File)NEW YORK – Longtime NBC News anchor Tom Brokaw, once television news' most popular broadcaster as he told viewers about the biggest events of that late 20th Century, said Friday that he's retiring from television. In 2013, Brokaw was diagnosed with multiple myeloma, an incurable blood cancer that affects the bone marrow. Brokaw said the coronavirus pandemic, which has killed more than 400,000 Americans in the past year, was the country's greatest test since the Civil War.