Arch Private Investigations - Our Expertise and Commitment

Full-Service Investigations Across Missouri

Arch Private Investigations handles cases for individuals, families, attorneys, insurance carriers, and businesses throughout St. Louis and the wider Missouri area. Our services cover surveillance, background checks, asset searches, domestic cases, insurance fraud, skip tracing, witness interviews, civil litigation support, and corporate investigations. Whether you need one piece of the puzzle or a full investigative workup, we have the licensing, the tools, and the field experience to deliver what you need.

Your Case Gets Our Full Attention

We're not a call center that farms your case out to whoever is available. When you hire Arch, you work directly with our lead investigator from the first consultation through the final report. You get regular updates, direct communication, and someone who actually knows your file. That kind of access matters when the details of your case are sensitive and the stakes are personal.

Built On Facts, Not Assumptions

very investigation we take on follows the same principle: start with what's known, verify everything, assume nothing. We don't cut corners or fill gaps with guesswork. Our process is methodical, legally compliant, and documented at every step so that when we hand you our findings, you're looking at facts that hold up in court, in a boardroom, or wherever the situation takes you.

Michael K. Adelstein | Founder & Lead Investigator

Arch Private Investigations was founded by Michael K. Adelstein, a licensed private investigator with a career spanning more than 25 years in the investigative field. His background includes work in law enforcement as a reserve police officer, asset protection investigations for major retailers, claims investigation for the City of Chicago, and ownership of private investigation agencies in both Illinois and Florida before establishing Arch in St. Louis in 2026. He holds a Master of Arts in Criminology and Criminal Justice from the University of Missouri-St. Louis and a Bachelor of Arts in Criminal Justice from Truman State University. That combination of fieldwork and formal education shapes how every case at Arch is approached: methodically, ethically, and with a focus on facts that hold up when it matters.

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Licensed and Insured

Every investigation is conducted by a fully licensed private investigator carrying proper insurance. No shortcuts, no gray areas, full legal compliance from start to finish.

Complete Discretion

Sensitive situations require equally careful handling. We always operate with total discretion and confidentiality, protecting your privacy and your interests at every stage of the process.

24/7 Availability

Cases don't follow business hours and neither do we. Our team is available around the clock for consultations, updates, and active investigations whenever the situation demands it.

Free Consultation

Not sure where to start? We offer free confidential consultations to help you understand your options, what an investigation involves, and whether we're the right fit for your case.

Expert Testimony

When your case goes to court, we don't just hand over a report. Our investigators provide professional expert witness testimony to support the findings and stand behind the work.

Nationwide Reach

Based in St. Louis, but not limited to it. Through our established professional network, we can extend investigative resources well beyond Missouri when your case requires it.

Multilingual Capability

Language shouldn't be a barrier to getting the truth. Our team provides investigative services in multiple languages, ensuring accurate communication during interviews, statements, and client consultations regardless of who's involved.

Advanced Technology

Modern investigations require modern tools. We use current surveillance equipment, database platforms, GPS tracking technology, and digital research methods to gather evidence efficiently and build cases that hold up under scrutiny.

Rapid Response

Some situations simply can't wait for a scheduled appointment. When a case is time-sensitive, our team mobilizes quickly to begin surveillance, secure evidence, or conduct critical interviews before the window closes.