• Why You Should Hire Us


      Uncover the Truth About the Situation




      Wondering if your suspicions are valid? Tired of being in the dark, when you should be in the know? Alessi Investigations is a full-service private investigation service in Tulsa, Oklahoma. Our licensed and bonded investigator continues to assist individuals throughout the area by:

      • Finding out if a current partner is cheating, stealing, etc. 
      • Determining if a former partner is properly taking care of a child
      • Gathering information about a criminal case for evidence 
      • Making sure a workers comp claim is not fraudulent 

      Alessi Investigations can also assist with fraud investigations, service of process, missing person locations and other services. You can trust our experienced P.I. to obtain the information you need to make the right decisions moving forward. 


      Start uncovering the truth – call Alessi Investigations of Tulsa, OK today at 918-500-2386.

    • Contact Us Today


    • Our Services

    • Criminal Defense

      Criminal Defense

    • Child Custudy

      Child Custudy

    • Marital Infidelity

      Marital Infidelity

    • Workers Comp

      Workers Comp

    • Alessi Investigations Has Years Of Experience. Trust The Experts.

    • Why Choose Us?

    • What Our Clients Say

    • My ex-fianc√© repeatedly violated his restraining order by coming over and threatening me, slashing my tires and breaking my windows. The police could never respond in time to catch him. Alessi Investigations caught him and he finally went to jail. I never slept better than that first night, not having to worry about someone breaking down my door trying to kill me. Thank You SO much for everything you did!

      Amber J.

    • Nathan Alessi is a laid back and gregarious man, with a drive to do the right thing, find the truth, and is honorable, even when he doesn't have to be. I know several people who have used him, (Some at my recommendation) and none have been disappointed. If I had a need for a P.I. , there is no other I would turn to.

      Stuart D.

    • I've used Alessi Investigation multiple times and I'm never disappointed! Nathan is hands down the best investigator in the state!!

      Greg D.