top of page

Private Detective and DNA Test

Updated: Mar 26

During an information, advisory, assistance, or investigative mission, a detective may resort to genetic fingerprint analysis to carry out the investigation successfully. The use of DNA can thus become a powerful tool that must, however, be conducted within legal bounds. So, how can a detective go about gathering the evidence they need?

How can a detective use DNA in an investigation?

First, it's important to note that the law on bioethics maintains a common foundation worldwide: "It is considered illegal to use a person's DNA without their knowledge... consent for a DNA test must be explicit and must not be subject to any external obligation." Therefore, one can conclude that the maneuvering space is very limited during a genetic analysis procedure. However, alternatives remain possible...

Genetic analysis and anonymity

In a private DNA test, participants' data are inherently anonymous because laboratories have no control over the participants' statements regarding the information provided. Moreover, the creation of a DNA profile in the laboratory cannot in any way define the individual's civil identity. In this sense, the genetic profiles stored in databases are annotated only under a test identification number that cannot be linked to the clients' declarations since they are uncertain.

Furthermore, laboratories are not authorized to establish national genetic fingerprint databases. In this regard, genetic data cannot be used for purposes other than those stated in the consent signed by the participants. And no request for data disclosure can be made to third parties.

On the contrary, a legal test aims precisely to control the identity of the participants. It is therefore unthinkable to carry them out anonymously. This is why, during a judicial test, the identity of the participants is checked before the samples are taken in an accredited laboratory.

Identity declaration during a DNA test

ou can notice that the procedure raises an issue! How can we ensure that the sample sent corresponds to the declared identity of the participant?

This is how a private detective could use the genetic tool to his advantage to conduct DNA tests or kinship comparisons without the owner needing to provide consent. Since, for the laboratory, the declaration and consent have been duly approved on the requested form.

In practice, it can happen like this:

  • Collection of a biological sample from a person, without their knowledge

  • Ordering a DNA test with a private laboratory

  • Consent is provided under a different identity

There is no way for the laboratory to verify whether the received sample corresponds to the declared identity or not. And there is no way for the person who has been tested without their knowledge to prove or ask the laboratory for the result and the withdrawal of their consent. Because the analysis is protected in the name of a third party.

Prevention Measures

In order to prevent discreetly conducted DNA tests, laboratories are intensifying their efforts by demanding even more verifications during sample collection. That's why the use of saliva samples is recommended for biological relationship tests. Logically, obtaining buccal swabs using saliva samples is generally a sign of the participant's consent.

The laboratory may also request a valid reason when ordering the DNA test to eliminate any obvious inconsistencies.

The use of a discreet sample

The discreet sample can take an infinite number of forms, and the detective can indeed request an analysis for any type of support to retrieve the DNA present on it. However, a distinction must be made between samples that come directly from the person (direct samples) and objects that have been used, consumed, or handled (indirect samples).

Direct Discreet Samples:

Hair, nails, blood samples (tube or swab), semen (condom or stain), medical procedure samples, dental samples, biopsy, muscle sample, bones, ashes...

Indirect Discreet Samples:

  • Personal items such as a toothbrush, a hairbrush, razor, glasses...

  • Consumable items containing DNA such as cigarette butts, chewing gum, tissue, toothpick, cotton swab, sanitary napkin (tampon), condom...

Reliability of a discreet sample:

When a laboratory receives a sample, the first step in the analysis is the extraction of DNA from the submitted support to create the person's genetic profile. At this stage of the analysis, not all samples provide the same success rate in the DNA extraction process.

The quality of the extraction depends on several factors such as storage or the date of collection, but especially the type of sample. It is easier to extract DNA from direct samples or samples containing emanations from the person, such as a bloodstain, semen, mucus, or earwax.

A reliable sample is one that will provide enough genetic information for the DNA test you have ordered without too much difficulty. It is essential to prioritize a specific type of sample, follow the collection method, and preserve the sample to avoid any contamination.

The reliability of a sample depends on its extraction rate. Under no circumstances can a poor sample provide a false result.

  • If your sample does not contain enough genetic information for the test, the laboratory will ask you to provide a new sample to continue the analysis.

  • If you receive your results, it means that your samples have been correctly analyzed, the collections have gone well, and a genetic profile has been found.

Genetic Detection Analyses

Unlike the creation of a genetic profile derived from a person's DNA and therefore belonging to their personal property, it is also possible to use genetic detection analyses that provide very limited access to biological information.

It is possible to analyze a sample to determine the presence or absence of DNA on it. This detection provides results on the gender of the DNA (male or female) and the number of DNA found by the laboratory. However, you will not have access to the person's genetic profile in any case.

Similarly, there are detections of seminal fluid (sperm) on samples. This detection will determine if the sample sent to the laboratory contains semen or not.

Private Detective and Genealogical Research

A private detective can also conduct genealogical research to reconstruct a family tree, find missing relatives, or locate heirs in the context of an inheritance (succession genealogy).

Some detectives specialize in this field to become genetic genealogists and assist you with expertise and know-how in the search for missing relatives or heirs.

It is a time-consuming task to which the detective devotes a lot of time, tracing family ties generation after generation to identify members of a lineage.


bottom of page