( CNN ) -- Mexican authorities searching a man with a bulge under his shirt at the airport in the nation 's capital found 18 monkeys hidden beneath his clothes , police said . Investigators grew suspicious after Roberto Sol Cabrera Zavaleta , 38 , became `` markedly nervous '' when asked what he was transporting , Mexico 's Public Safety Department said . Two of the tiny titi monkeys he was carrying in a belt were dead , the department said in a statement , and 16 of them survived the journey from Lima , Peru . Cabrera has been detained as authorities continue their investigation , the statement said . In an interview with authorities released by police , Cabrera said he first carried the monkeys in his suitcase , but then hid the animals in his clothes so they would not be harmed by X-ray machines at the airport . Cabrera described the animals as `` pets '' and told authorities he had purchased them for $ 30 . Titi monkeys are protected endangered species requiring a permit for possession , police said . Images released by police show the tiny creatures , many of which are tied up in pouches , squirming in a cardboard box .
Police say the actor was carrying 18 monkeys in a belt under his shirt . Police say they grew suspicious when Cabrera was nervous during filming . Titi monkeys are an endangered species requiring registration for ownership .