We are a specialized investigative agency with roots in San Francisco, California and branch offices in Salem, Oregon; Phoenix, Arizona; and a regional office in San Jose, Costa Rica covering all of Latin America.

Founded in 1978, our firm specializes in litigation support, financial background investigations and due diligence on individuals and businesses. We provide superior investigative reports to major law firms, plaintiffs’ attorneys, insurance companies, commercial landlords and pension funds throughout the United States, Latin America, Asia and Europe.

As we maintain an active membership in the most prestigious investigative associations in the world, we have an established global network of exceptional professionals that can execute our services with the same high-level of professionalism on a worldwide basis.

Our investigators provide thoroughly researched and detailed reports compiled with both public databases and our impeccable private sources developed over the past 40 years. We carefully review and analyze information from dozens of public and private databases and industry sources to produce a comprehensive and useful report to assist your information needs.

Our Investigators

Mary Nikas

Ms. Mary Nikas has been a private investigator for over 20 years, both as a manager and as the owner of her own investigative firm. She comes from a background in both the real estate and financial industries prior to entering the investigative industry in 1993. She has an uncanny ability to accumulate and analyze massive amounts of data and produce a concise, detailed report for a winning strategy.

Seth Derish

Of Counsel

Mr. Seth Derish is the co-regional director for Central and South America for the Council of International Investigators, a prestigious international association with members in more than 50 countries. He is also a lifetime member of the World Association of Detectives, the largest and oldest association in the world. His 40 years in the industry have led him to the four corners of the globe. He was outside investigator for the Financial Crisis Inquiry Commission, a congressional commission tasked with investigating the Great Recession; was sent to Latin America by the U.S. Southern Command to investigate military improprieties; and was lead investigator assigned to investigate assets on a former Latin American president who allegedly stole over $200 million, amongst other more routine cases.

Our Services

Due Diligence

  • Business Entities: Structure, Officers/Directors, Legal Status, Operations, Location, Litigation, Media, Tax Status
  • Individuals: Business Involvement, Employment, Education, Litigation, Media
  • Site Visits: Photo and Video Verifications (Size/Operations)

Financial Investigations

  • Asset Verification & Underwriting Research
  • Deficiency Judgment - Personal Guarantor Asset Research
  • Corporate Structure and Principal Research
  • Commercial & Personal Loan Underwriting Research
  • Bankruptcy - Asset Verification & Fraud

Real Estate Investigations

  • Real Estate Ownership & Encumbrance Research
  • Real Estate Transaction & Loan Fraud Investigations
  • Landlord-Tenant Disputes: Primary Residence/Ellis Act
  • Real Property Title Research (Nationwide)
  • Real Estate Disclosure Disputes / Extensive Interviews
  • Quiet Title / Clouded Title / Heir Identification and Locates

Pension/Union Investigations

  • Withdrawal Liability Reports (Signatory Employer & Principals)
  • Corporate Structure/History & Ownership Analysis
  • Pre and Post-Judgment Asset Investigations
  • Affiliated Entity Research (Duel-Shop Investigation)
  • Prevailing Wage Investigations (Surveillance/Interviews)
  • Commercial/Residential Tenant Identification (Income Property)

Personal Injury/Negligence

  • Industrial / Motor Vehicle / Personal Injury
  • Witness Locates & Interviews
  • Defendant Background Research
  • Under-Insurance Financial Investigations
  • Premises Liability / Slip & Fall Investigations
  • Professional Negligence Investigations
  • Surveillance / Field Investigations

International Investigations


  • Investment Fraud
  • Death Verifications
  • Missing Persons/Worldwide Location Reports
  • Corporate/Business Operation Verification
  • Insurance Claims and Accident Reports

Coverage Regions

San Francisco Bay Area
Nationwide Coverage
Phoenix, Arizona
Salem and Portland, Oregon
San Jose, Costa Rica
Central America (Parts Of)
Worldwide Affiliates



California BSIS #12656
Oregon DPSST #33709
Costa Rica ID: 3-101-239587


Council of International Investigators (C.I.I.)
World Association of Detectives (W.A.D.)
California Association of Licensed Investigators
Oregon Association of Licensed Investigators
INTELLENET International Intelligence


Domestic Research
Ms. Mary Nikas
Derish Associates, Inc.
San Francisco, California
Office: (415) 459-1448
Email: US-Inv@PrivateEyes.com

International Research
Mr. Seth Derish
Costa Rica Investigations, S.A.
San Jose, Costa Rica
U.S. Toll Free: (415) 648-7007
Email: CR-Inv@PrivateEyes.com