How was Enrique captured in each of his previous attempts to travel north, according to the author in Chapter 2?

Enrique was first captured in Veracruz on a train and deported. His subsequent attempt, he was also caught on the trains. His third and fourth attempts led to his being robbed by police. He was caught in Mexico City his fifth attempt. On his sixth, he made it to the Rio Grande but was seized by immigration agents.