This is a toxicologist's worst-case scenario. A body arrives with all of the symptoms of a lethal drug overdose. However, weeks later, the examination of the blood sample yields clean results. The cause, scientists now warn, may not be a lack of medications but rather the presence of a new murderer who destroys its evidence. 

Official records drastically undercount deaths caused by nitazenes, a potent class of synthetic opioids, according to new research from King's College London (KCL). According to the study, which was published in the journal Clinical Toxicology, up to one in every three nitazene-related deaths could be overlooked because the medication degrades in post-mortem blood samples before testing is performed. 

Nitazenes are synthetic opioids that can be up to 500 times more potent than heroin. They were developed decades ago as pain relievers but were never approved for medical usage due to their high potency. Today, they are inexpensive to create and are increasingly available on the unregulated drug market, where they are frequently mixed with or sold as other narcotics. 

Unlike many medications, nitazenes have a hazardous chemical property: they do not remain stable in the circulation after death. 

In the United Kingdom, post-mortem blood samples normally take about a month to reach toxicology labs for analysis. KCL researchers used anaesthetised animal models and real-world handling settings to investigate what happens to nitazenes during this delay. 

Their findings were startling. Only 14% of the initial nitazene was detectable by the time testing would ordinarily take place. Simply put, the majority of the medicine has already degraded, similar to how a chemical evaporates before it can be detected. 

"This means a lethal dose can look like a trace amount, or nothing at all, by the time it reaches the lab," the researchers said. 

The UK National Crime Agency (NCA) reported 333 nitazene-related deaths in 2024. However, the KCL team believes that this figure only provides a partial picture. 

Using mortality data from the UK National Programme on Substance Use Mortality (NPSUM), the researchers projected deaths in Birmingham in 2023 and discovered a 33% increase in drug-related fatalities that could not be explained by known substances. They contend that nitazene deaths went undiscovered because the medication deteriorated prior to testing. 

Dr Caroline Copeland, Senior Lecturer in Pharmacology and Toxicology at King's College London, has cautioned that the repercussions are significant. 

"If nitazenes are degrading in post-mortem blood samples, then we are almost certainly undercounting the true number of deaths that they are causing," according to her. "That means we're trying to tackle a crisis using incomplete data." 

Undercounting deaths does more than simply affect statistics. It shapes policy. 

"When we don't measure a problem properly, we don't design the right interventions," Dr Copeland told me. "The inevitable consequence is that preventable deaths will continue." 

Families are also impacted. When toxicology testing fails to find the substance, death certificates may state "natural causes" or return an open verdict. Loved ones are left without clear explanations, and communities are unaware of the actual extent of their suffering. 

Scientists believe the solution rests in faster testing and better forensic technologies. Instead of only looking for the drug, scientists must also detect the breakdown products that nitazenes produce. 

"Better science leads to better surveillance, and better surveillance will save lives," according to Dr Copeland. 

As nitazenes grow globally, experts warn that healthcare institutions may be dealing with a situation they cannot fully understand – a lethal epidemic made invisible by chemistry.