Private investigators in Norway

For consumers and businesses. We deliver private investigation services 24-hours a day, 7 days a week. Our staff is based all over Norway and we have experience from police and intelligence. Discretion is guaranteed!

Time to read: 4 minutes

Etterforsker1 Gruppen AS or «Investigator1», is a Norwegian company that provides investigation services to consumers and companies. Members of our staff are highly skilled investigators and we specialise in technology. Etterforsker1 Gruppen is the largest private investigation bureau in Norway, covering the whole of Scandinavia.

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Our headquarters is located in the Oslo-area, close to the international airport with direct connections to Amsterdam, Copenhagen and London.

We have offices in many cities in Scandinavia, including Oslo, Bergen, Stavanger, Trondheim and Copenhagen.

The company was founded by private investigator Thomas Mathiesen in 2014.

Feel free to contact us at any time:  +47 21 60 81 78 (Norway) +31 70 80 80 212 (The Netherlands) or send an email to

Members of organizations

We are members of World Association of Detectives, The Norwegian Business and Industry Security Council (NSR), Asis International and The Federation of Norwegian Enterprise (VIRKE).

World Association of Detectives
VIRKE logo

Our services includes, but is not limited to:

Asset tracing

Asset tracing

Asset tracing in Norway and Scandinavia. We find assets that are hidden.

We have access to databases and we have agents on the ground to find and identify the assets.

Child Custody

Child custody

Divorced parents often fight over child custody. We help you to stand stronger in child custody cases.

We are available 24 hours a day to find the proof you need!

Due Diligence

Due Diligence

Do you need more information about a person, a company or an organization? Let us help you out!

We are discreet, we gather information and we are on the ground.

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Handwriting forensics

Handwriting forensics

Documents may be falsified and anonomous threat letters are sent. We help you find the truth.

Our experts in handwriting forensics reveals fake signatures and documents.



What does your partner do in his/her sparetime? We help you find the truth.

We recover deleted sms’es, we investigate your partner and we find the truth!



Many of us needs an investigator every now and then. We accept more or less any assignment!

We search for you, we investigate for you and we document for you!

Mystery shopping and control purchase

Mystery shopping

Our PI’s check what is being sold and how products/services are being promoted.

We have PI’s all over Norway and we respond quickly.



You may wonder where a person is and who a person meets. This can be your child, your employee etc.

We have more than 45 PI’s on the ground all over Norway – Ready to carry out surveillance for you today!



We provide advice and consultancy in security. We are specialised in technology and can help you find the best solutions for your requirements.

Our professionals help you with anything related to security and legal questions in Norway. We cooperate with lawyers to give you the best service possible.

Feel free to contact us at any time:  +47 21 60 81 78 (Norway) +31 70 80 80 212 (The Netherlands) or send an email to

Our contact information

Head office address: Gokstadveien 18, 3216 Sandefjord, Norway

Phone number: +47 21 60 81 78.

Our email addresses:

  • General inquiries:
  • Suppliers:
  • Press:

Other helpful information about us

Chamber of commerce number (Norway): 913 193 458 (link to Chamber of commerce).
NATO NCAGE: N6175 (link to ncage).

Read our cookie-policy here (in Norwegian).

Read our terms and conditions here (in Norwegian).

Dagens Næringsliv Gaselle Etterforsker1

We are proud to be ranked a Gaselle company by the Norwegian finance newspaper Dagens Næringsliv.

Contact us (consultation is free of charge)

Discretion is guaranteed.

Telephone: +47 21 60 81 78

    Etterforsker1 in the news (NRK)

    Etterforsker1 på NRK Dagsrevyen
    NRK news visiting Etterforsker1

    InsiderFEM episode about Etterforsker1

    Etterforsker1 Insider TVNorge Marte Bratberg
    Discovery+ and Marte Bratberg made a documentary about our company. See how we work in this documentary.

    Private investigator podcast

    Privatetterforsker podcast med Thomas Matheisen
    Listen to the private investigator podcast on Spotify and Youtube. Contact us if you have questions that you would like us to discuss in this podcast.

    Hele verden

    Vi holder til i Norge, men vi reiser verden rundt for å etterforske for deg! Gjennom våre erfarne partnere har vi mulighet til å utføre tjenester i hele verden på kort varsel.

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