We are the best team to cope with any investigative task!

Portland Private Investigators,  is an Oregon State Licensed Professional Private Investigation agency.

Duane Larson, owner of Cornerstone Investigative Services, Inc, is a dedicated investigator with over 30 years combined private investigation and law enforcement experience.

Cornerstone Investigative Services, Inc is a Private Detective Agency with a track record of delivering first-class professional investigative results throughout Oregon and Nationwide.

Our office is located in Downtown Portland in the World Trade Center.

Our Investigative Team is comprised of Licensed Private Investigators with extensive investigative experience including surveillance and covert undercover investigations.  They are not identified here by the nature of their assignments.  This protects their status and offers a greater level of security and confidentiality for our clients.

Our Team

Duane Larson

President and Investigative Services Manager

Duane Larson, is a Licensed private investigator with over thirty years combined law enforcement and investigative experience. During his many years as an investigator, he has conducted numerous civil, criminal and corporate investigations.   Duane is the current manager of investigative services for PDX PI, LLC.

Tom Turner


Tom Turner,  is the co-founder of Portland Private Investigators and is a veteran private investigator with over thirty years investigative experience, licensed in Oregon and California.  He is an investigator, author, Instructor and lecturer.  His experience has been in both the public and private sectors.

Susan Newton


Susan Newton (1947 – 2016) was one of the founders of Portland Private Investigators.  Her energy and knowledge made it possible to become the agency we are today.  We mourn her passing, but know that her spirit continues with us and guides us.  Susan was an exceptional investigator, but more importantly, she was a decent, kind and honorable person.


Our staff of licensed, experienced private investigators will handle all of your legal and personal investigative needs in the most professional, skilled, and cost effective manner.


Cornerstone Investigative Services, Inc – Portland Private Investigators
One World Trade Center
121 SW Salmon St., Suite 1100
Portland, OR 97204
By Appointment Only
(503) 575-2836


Oregon State Lic. 69507

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