A new, non-invasive fingerprint test can determine whether cocaine has been ingested, Science Daily reports.

Researchers used a process called mass spectrometry to analyze fingerprints of patients attending drug treatment services. The fingerprints were tested against saliva samples to determine whether the two tests correlated.

Previous fingerprint tests have only been able to determine whether a person had touched cocaine, but not whether they have actually ingested the drug. The researchers, led by the University of Surrey, showed they were able to detect chemical traces of cocaine in the residue left by the patients’ fingerprints.

“When someone has taken cocaine, they excrete traces of benzoylecgonine and methylecgonine as they metabolize the drug, and these chemical indicators are present in fingerprint residue,” said lead author of the study Dr. Melanie Bailey from the University of Surrey.

The method is a less invasive means of drug testing. Traditional testing methods have limitations, Science Daily notes: “For example, blood testing requires trained staff and there are privacy concerns about urine testing.”

Dr. Bailey said a future portable fingerprint drug test is already in the works, and could be deployed for law enforcement agencies to use within the next decade.

“The beauty of this method is that, not only is it non-invasive and more hygienic than testing blood or saliva, it can’t be faked,” said Dr. Bailey.