About Private Investigator

Martin Geisler created Known Stranger Investigations, LLC. to assist law enforcement, the family in need, as well as, the person who has been reported as “Missing,” with the goal of closing out missing person cases.      

Known Stranger Investigations can be a secondary source, providing the assistance of time and manpower in the search of non-criminal missing person cases pertaining to runaways, suicidal persons, and lost people with Dementia/Alzheimer’s.

In 1993, while in college, Martin came across the term “Known Stranger” in a textbook.  The textbook revealed that many people who were harmed, kidnapped, or murdered, knew the assailant.  Over the years, the term “Known Stranger” slowly replaced the motto “Stranger Danger” (an unknown perpetrator).  In essence, the majority of serious, violent, and missing person cases are primarily committed by someone that is known to the victim. 

Similarly, runaways, suicidal persons, and missing people with Dementia/Alzheimer’s called have an association with the term Known Stranger, as defined by Known Stranger Investigations, LLC.

Martin has vast knowledge of the field of Criminology.       

Martin earned a Bachelor of Science Degree in Criminal Justice and a Master’s Degree in Sociology / Criminology.

More recently, Martin retired as a Peace Officer after 21-years of service.  Having read, scrutinized, and summarized over 3,000 police reports from simple drug offenses to high-profile murder cases; Martin wrote and submitted Sentencing Reports to the California State Superior Courts.

From 1999 through 2001, Martin worked at a missing children’s organization called Child Quest International.  He assisted in over 100 missing person cases and helped solve several high-profile missing person cases.  Some cases which were classified as “runaway” turned into murder cases and some cases which were deemed “suspicious circumstances” turned out to be runaway cases. 

Furthermore, Martin assisted in locating people who left home threatening to commit suicide and elderly people who eloped from their residence.  Martin found that there were not many organizations to turn to for assistance in non-criminal missing person cases, when searching for someone who is suicidal or someone who is lost and diagnosed with Dementia/Alzheimer’s.