Truth Verifier Systems, Inc.

Truth Verifier Systems, Inc. (TVSI) is a private detective agency in Mandaluyong City, Metro Manila, founded in May 1966 as the first private investigator agency and lie detector company in the Philippines. It presents itself as the country's first and leading licensed private detective agency, licensed by the Philippine National Police under license PDA-001 as published on its own site.

The agency specializes in background investigation, fraud investigation, surveillance and undercover work, locating persons or properties, record checking, lifestyle checking and evidence gathering, together with its computerized lie detector testing. Its site states that it serves government and private-sector clients as well as local and foreign individuals across the country.

TVSI states that it was the first ISO-certified private detective agency for lie detector testing, detective and investigative services and training, and that the Philippine National Police named it a Hall of Fame Best Private Detective Agency. Its main office is in Mandaluyong City and it publishes a branch office in Sta. Rosa, Laguna, for the Calabarzon area.