Motivating cooperation in official police interviews is a central professional challenge across jurisdictions and cultures. Rapport-building is regarded as a critical antecedent of interviewee cooperation, but relatively little is known about how rapport is developed in practice. A total of 123 experienced intelligence and investigative interviewers from five Asian-Pacific jurisdictions (Australia, Indonesia, Philippines, South Korea and Sri Lanka) participated in in-depth interviews (mean 68 min) about rapport-building techniques used with high-value interviewees. The majority of participants had more than 10 years' experience and 63% had conducted between 100 and 500 interviews. Responses were recorded, transcribed and de-identified for systematic deductive analysis according to the principles of persuasion outlined by Cialdini, to assess the nature and extent of forms of social influence strategies applied. Reported rapport-development techniques were classifiable as one or more of these six principles of persuasion: reciprocity, commitment, social proof, authority, liking and scarcity. Results revealed that liking and reciprocity were the principles that encompassed the most ubiquitously and frequently reported rapport-development strategies across jurisdictions. Liking was established through similarity and humour, although at times dissimilarity was effective. Few practitioners simulated liking; the majority were sincere. Techniques encompassed by the principles of authority, commitment-consistency and social proof were culture-bound and more diverse. Results confirmed the generalisability of social influence theory to the policing context across diverse legal systems and cultures. By applying psychological theory to advance understanding of rapport-building, best practices and policies were identified in a field where few standards exist. Notwithstanding the limitations of self-reports, strong practitioner support emerged for the effectiveness of noncoercive social persuasion strategies in high-stakes police interviews.