Texas License: A-11847 | Louisiana License: 7311-011910-LA

Alabama License: 395 | Tennessee License: 8510

Texas Institute of Investigation

The Texas Institute of Investigations was founded by Mark Gillespie to offer a variety of instruction and courses regarding private investigations, forensic science, safety and security, personal defense and handgun licensing/use/safety.  Courses are offered to PIs and security professionals as a source for continuing education (CE); and to the general public as a way of introducing them to the PI profession. 

Mark Gillespie is certified by the Texas Department of Public Safety Regulatory Services Division Private Security Board to award continuing education (CE) credits for Texas PSB licensees and registrants.


  • So You Want To Be A PI?
  • Finding Your Niche
  • Death Investigations
  • Crime Scene Investigations
  • Forensic Techniques and Evidence Collection
  • Junk Science: What PIs and Criminal Defense Attorneys Need to Know About Forensic Science
  • Forensic Science for the PI
  • Forensic Science for Attorneys
  • Interviewing Techniques and Affidavit Preparation
  • Surveillance Training
  • Missing Persons Investigations
  • Human Trafficking Investigations
  • Handgun, LTC & CHL Training
  • College Student Safety and Security Awareness
  • Safety and Security for the Real Estate Professional
  • Ethics

A Word from Our Clients

Contact Us

2501 South Bagdad RD., Suite B,
Leander, TX 78641