A person who gathers information for news or publication; often used for journalists, reporters, or anyone conducting interviews for a story.
The reporter was trying to get the details of the incident.
The interviewer requested an interview with the famous author.
インタビュアー is a loanword for 'interviewer,' often used in broadcast or formal interview settings. 取材者 is broader and can refer to any information gatherer, not just in interview contexts.
Compound of 取材 (shuzai, 'news gathering, coverage') + 者 (sha, 'person'). The derivation is straightforward from its components.