Jane Klinger, right, chief conservator for the United States Holocaust Memorial Museum, talks with Mansour al-Omari, left, a Syrian human-rights activist documenting cases of people who have disappeared under President Bashar Assad's government, who shows scraps of fabric with the names of fellow inmates he is presenting to the U.S. Holocaust Memorial Museum for preservation at the conservation center, Tuesday, Aug. 8, 2017, in Bowie, Md. (AP Photo/Susan Walsh)
Mansour al-Omari, a Syrian human-rights activist documenting cases of people who have disappeared under President Bashar Assad's government, shows scraps of fabric with the names of fellow inmates he is presenting to the U.S. Holocaust Memorial Museum for preservation at the conservation center, Tuesday, Aug. 8, 2017, in Bowie, Md. (AP Photo/Susan Walsh)
Mansour al-Omari, a Syrian human-rights activist documenting cases of people who have disappeared under President Bashar Assad's government, shows scraps of fabric with the names of fellow inmates he is presenting to the U.S. Holocaust Memorial Museum for preservation at the conservation center, Tuesday, Aug. 8, 2017, in Bowie, Md. (AP Photo/Susan Walsh)
Mansour al-Omari, a Syrian human-rights activist documenting cases of people who have disappeared under President Bashar Assad's government, shows scraps of fabric with the names of fellow inmates he is presenting to the U.S. Holocaust Memorial Museum for preservation at the conservation center, Tuesday, Aug. 8, 2017, in Bowie, Md. (AP Photo/Susan Walsh)
Mansour al-Omari, a Syrian human-rights activist documenting cases of people who have disappeared under President Bashar Assad's government, talks about how he smuggled scraps of fabric with the names of fellow inmates out of Syria that he is presenting to the U.S. Holocaust Memorial Museum for preservation at the conservation center, Tuesday, Aug. 8, 2017, in Bowie, Md. (AP Photo/Susan Walsh)
Mansour al-Omari, a Syrian human-rights activist documenting cases of people who have disappeared under President Bashar Assad's government, shows scraps of fabric with the names of fellow inmates he is presenting to the U.S. Holocaust Memorial Museum for preservation at the conservation center, Tuesday, Aug. 8, 2017, in Bowie, Md. (AP Photo/Susan Walsh)