After spending 10 to 14 years captive in the jungle, 10 police and military officers were released by Colombia’s leftist FARC rebels on Apr. 2. They were the last “political prisoners” FARC had released as part of a prisoner swap with the government. Now, calls for the rebels to free their “economic prisoners”—civilians kidnapped for ransom—are rising, but there is one major difficulty: it’s not clear how many prisoners there are. While the NGO País Libre estimates 405 people remain in FARC’s hands, another, Nueva Esperanza, puts the number at 725. Fondelibertad, a government agency, said in 2011 that only 38 people remain. But estimating this number is next to impossible. Some families don’t report abductions, opting for direct negotiations instead. In 2008, Fondelibertad cut its count by deleting the oldest cases, further eroding the credibility of the numbers. And kidnapping proved lucrative enough—FARC collected ransoms as high as $1 million—that others took notice. Many victims could be in the hands of smaller groups claiming to be FARC. Meanwhile, FARC isn’t offering answers; just an observation that all the estimates are wrong.