ACM Investigations LLC

The history of private investigators in the United States can be traced back to the mid-1800s, when Allan Pinkerton formed the Pinkerton National Detective Agency. Pinkerton, a Scottish immigrant, had previously worked as a cooper and a police officer in Chicago. In 1850, he was appointed as the first detective in the city’s police force. However, after he exposed a ring of counterfeiters, he received death threats and resigned from the police force. He then founded his own agency, which became one of the most successful detective agencies in the country.

Pinkerton’s agency was known for taking on high-profile cases and was even hired by the U.S. government to track down criminals such as the notorious outlaw Jesse James. In 1874, Pinkerton’s agents were able to capture James’ accomplice, Robert Ford, which lead to the outlaw’s death. Pinkerton’s agency was also known for its role in strikebreaking, as well as providing security for railroads and other industries.

Another notable private investigator from this period was William J. Burns, who founded the William J. Burns International Detective Agency. Burns was known for his undercover work and had a reputation for being able to infiltrate any organization. He was also the head of the U.S. Bureau of Investigation (later renamed the Federal Bureau of Investigation) for a short time.

During the early 20th century, private investigators began to branch out and specialize in various fields. For example, many investigators began to focus on providing industrial espionage, while others specialized in insurance fraud investigations. With the advent of modern technology, private investigators began to use tools such as surveillance cameras and GPS tracking devices to aid in their investigations.

One of the more interesting private investigator from the 20th century is a man named “The Shadow” or Richard Gallagher, who is credited with coining the term “shadowing” as a synonym for surveillance. He was known to be one of the best tailing experts of his time and his case files include many celebrities and politicians.

In the present day, private investigators continue to be an important part of the criminal justice system, working alongside law enforcement to investigate crimes, gather evidence, and locate missing persons. With the growing reliance on technology, many private investigators now specialize in cybercrime investigations, tracking down online predators and identifying those involved in organized cybercrime.

Dates to remember:

  • 1850 – Allan Pinkerton starts his detective agency
  • 1874 – Allan Pinkerton’s agents capture Robert Ford
  • 1908 – William J. Burns founds the William J. Burns International Detective Agency


  • Walraven Kenneth

    This is very interesting, I’m a licensed Private Investigator/ Armed Security and I’m always looking for stories on Private Investigators, I have always wanted to be in this field of work and was finally able to get my license, thank you for sharing this and I’m glad I came across your business

    • Thank you for reading our blog and leaving a comment. We’re glad you found it interesting and relevant to your field as a licensed private investigator. We appreciate your interest in our business and are always happy to share our knowledge with others in the industry. Keep an eye on our blog for more stories and updates. If you need any assistance, feel free to reach out to us.

Leave a Reply

Refer Friends and Earn Cash Rewards!

Need help getting to the bottom of something? Let us assist you with our professional investigation services.

Ken Smith
Ken Smith
I used ACM Investigations to investigate employee theft in my business and was impressed with their professionalism and dedication. They provided the evidence we needed and I highly recommend their services to any business owner who suspects internal theft or fraud. Thank you.
Jody Smith
Jody Smith
Very happy with the services.
I recently had an emergency and needed someone to take care of my cat for a few days. I contacted ACM Investigations and their HouseWatch service was a lifesaver! Not only did they take great care of my furry friend, but they also sent me daily updates and pictures to put my mind at ease. I highly recommend their HouseWatch service to anyone in need of a trustworthy and reliable pet sitter or house sitter.
Adam Smith
Adam Smith
Great company and very helpful! Would recommend!
These folks are exceptional in the quality of work they provide, they were quick to help with our investigation of a suspect we're trying to locate. Very professional, highly recommended for your PI needs!