CAIRO: Ahmed Al-Yamani’s family went from joy of celebrating his daughter’s wedding to terror the next day, when masked troops stormed into their home in Sanaa, Yemen’s capital held by the country’s Iran-backed Houthi rebels, and arrested him. The family didn’t hear from him for months. His only crime, they suspect, was having worked for local humanitarian groups. Al-Yamani is among dozens of Yemeni workers with aid groups, United Nations agencies and nongovernmental organizations who have been detained since last year by the Houthis in the rebel-held northern part of the country.