What is ‘invisible theft detection powder’ and how is it used by the police in drug offences?
In complex drug importation investigations, the Australian Federal Police (AFP) sometimes use covert ‘controlled operations’ when investigating serious drug offences.
These operations are often used in cases involving the importation or distribution of border-controlled drugs. One common method involves the use of phosphorescent powder, which is a light-sensitive substance applied to substituted drug packages to link a person to an intercepted parcel.
Our criminal law firm have successfully challenged this type of evidence in court, exposing the flaws in how it is applied and interpreted.
How controlled operations work in drug investigations
Under Commonwealth law, the AFP and other federal agencies may conduct controlled operations when investigating organised crime syndicates or serious drug importation offences.
In these operations, authorities may:
Intercept a package believed to contain illicit drugs;
Remove the drugs and replace them with an inert substitute (such as flour or powder of similar appearance); and
Apply phosphorescent powder to the outside or contents of the parcel before allowing it to continue to its destination.
The powder is invisible to the eye but glows when exposed to ultraviolet (UV) light. Police then rely on UV testing at the time of arrest to claim that a suspect must have touched the package.
What is phosphorescent powder evidence?
Phosphorescent powder is used to detect physical contact. When a person handles the treated package, the fine powder transfers to their skin or clothing. Under UV light, the powder appears as a bright fluorescent residue.
In theory, this can be used to show that someone physically touched or opened a substituted parcel. However, the evidence is circumstantial as it does not prove possession, knowledge, or intent to import drugs. It only suggests possible contact with the item.
The flaws in phosphorescent powder testing
In practice, this technique has several scientific and evidentiary weaknesses.
Ease of transferability - The powder is designed to cling to almost any surface and can easily spread to other people or objects. A person may test positive simply by touching an area or surface where the powder has been transferred.
Cross-contamination - During reconstruction or delivery, the powder can attach to police gloves, packaging, or furniture, contaminating other items or surfaces.
Household interference - Many ordinary household substances can also fluoresce under UV light, such as potentially detergent, toothpaste, tonic water, body fluids, petroleum jelly, and olive oil, making it difficult to distinguish phosphorescent powder from other materials.
Because of these limitations, defence lawyers often challenge the reliability of UV testing and the chain of custody for any treated package.
How can this evidence be challenged in drug cases?
Our criminal defence lawyers have successfully defended clients where the prosecution relied heavily on phosphorescent powder testing. In these cases, we focused on:
The scientific reliability and contamination risk of the powder;
Whether proper forensic and evidentiary protocols were followed;
Whether the alleged ‘contact’ could be explained by secondary transfer; and
Whether the evidence, even if accepted, proved the essential elements of possession or knowledge.
Where these arguments are properly presented, courts may give little weight to the UV test results or exclude them entirely.
Choosing the best drug lawyer in Brisbane
If you are under investigation or have been charged following a controlled operation or drug importation offence, early legal advice is critical. Federal investigations move quickly and often involve covert surveillance, intercepted communications, and forensic testing that must be carefully examined.
Our criminal defence lawyers regularly act in high-level Commonwealth prosecutions involving the Australian Federal Police, Australian Border Force, and the Commonwealth Director of Public Prosecutions. Our team are available for a confidential discussion about your case. No booking required.
📞 Speak to our leading Brisbane Criminal Lawyers on (07) 3012 6531 for a confidential discussion about your case. You can also request a confidential callback by filling in our Quick Enquiry form, which also includes access to our free guide 16 Things You Need to Do Now if Charged with a Criminal Offence.
The information provided is general in nature and does not constitute legal advice. Please contact our Brisbane criminal lawyers for specific advice about your case.
Last updated November 2025