The United Nations investigators assembled in the departure hall of Sanaa’s airport were preparing to leave with precious evidence: laptops and external drives collected from the staff of the World Health Organization. These computers, they believed, contained proof of corruption and fraud within the UN agency’s office in Yemen. But before they could board their flight out, armed militiamen from Houthis ruling northern Yemen marched into the hall and confiscated the computers, according to six former and current aid officials, the Associated Press (AP) reported. The stunned investigators were left unharmed, but flew out without the telltale devices. Houthis had been tipped off by a WHO staffer with connections to the militia movement who feared her theft of aid funding would be uncovered, according to the six former and current officials who spoke on condition of anonymity because the seizure of the computers had not previously been made public. The October 2018 scene at the Sanaa airport is another episode in the continuing struggle over corruption that has diverted donated food, medicine, fuel and money from desperate Yemenis. More than a dozen UN aid workers deployed to deal with the wartime humanitarian crisis have been accused of joining with combatants on all sides to enrich themselves from the billions of dollars in donated aid flowing into the country, according to individuals with knowledge of internal UN investigations and confidential documents reviewed by AP. Yemeni activists said the actions by the UN agencies were welcome but fell short of the kind of investigation needed to track the millions of dollars in supplies and money from aid programs that have gone missing. Over the past three months, the activists have been pushing for aid transparency in an online campaign called “Where Is The Money?” They demand that UN and international agencies provide financial reports on how the hundreds of millions of dollars pouring into Yemen since 2015 have been spent. Last year, the agency said international donors pledged $2 billion for humanitarian efforts in Yemen. The UN has responded with an online campaign of its own called “Check Our Results,” showing programs implemented in Yemen. The campaign does not provide detailed financial reports on how aid money is spent. “We see big numbers, billions of dollars reaching Yemen, and we don’t know where they go,” Feda Yahia, a “Where is the Money?” activist, said in a video for the campaign. Also, internal UN reports from 2016 and 2017 obtained by the AP show several incidents where trucks carrying medical supplies were hijacked by Houthis in the battleground province of Taiz. The supplies were later given to Houthi militants on the front lines. An official who help draft the reports said it was “obvious there were some individuals who were working with Houthis behind the scene because there was coordination on the movement of trucks.” Another official said the UN’s inability or unwillingness to address the alleged corruption in its aid programs harmed the agency’s efforts to help Yemenis affected by the war. “This is scandalous to any agency and ruins the impartiality of UN,” the aid official said.