Which action is a method to investigate human smuggling?

Interviewing suspected noncitizens is a direct method employed in investigating human smuggling because it allows agents to gather firsthand information about the individuals involved in potential smuggling operations. This investigative technique helps agents understand the circumstances surrounding a person's arrival, their journey, and the individuals who may be orchestrating the smuggling. During these interviews, agents can identify patterns, connections, and other vital intelligence that can lead to broader investigations and eventual prosecutions.

In contrast, hosting public awareness campaigns, conducting community outreach programs, and establishing shelters for immigrants tend to focus more on prevention, support, and community relations rather than the direct investigative aspect of human smuggling. While these activities can contribute to the overall understanding and reduction of human smuggling, they do not specifically serve as a method of investigation. Instead, they aim to educate the public, provide assistance to immigrants, and build trust within communities, which are essential components in combating human smuggling but not investigative methods in themselves.