Eloy Bárbaro Cardoso, an 18-year-old student, was also swept up in the demonstrations. His mother, Servilia Pedroso, said he was leaving his grandmother’s house in Havana’s poor La Guinera neighborhood on July 12 when he ran into a crowd protesting the lack of food and medicine. The teenager was detained several days later, accused of public disorder, and freed after paying a fine of 2,000 Cuban pesos — around $83 — his mother said.