PETALING JAYA (THE STAR/ASIA NEWS NETWORK) - Unknown until now, Malaysian investigators have been using a tool that is more powerful than the lie detector polygraph. It can tell with certainty when someone is lying based on his voice, according to its creator.

The Forensic Voice Stress Analyser (FVSA) has been used with amazing success to determine who were involved in the Lahad Datu incursion last year.

Australian Security Risk consultant John W. Ryan, who developed the software, said the FVSA "picks up and displays unheard frequencies that human physiology produces and the voice carries".

"So, when stress is applied (during interrogation), the subconscious changes the frequency, and this reaction, which indicates whether the person is telling the truth or lying, can be seen on the screen," added Ryan, who demonstrated how the system works to The Star last Friday.

The polygraph, on the other hand, measures and records several physiological indices such as blood pressure, pulse, respiration, and skin conductivity while the subject is answering a series of questions.

The software can be installed on ordinary notebook computers and a small microphone is used to record the results. And suspects can be questioned in any language.

Ryan said the system saves time and resources.

"Imagine two detectives having to interview 12 suspects. The FVSA will help them narrow their focus," he said.

Ryan, who was in Kuala Lumpur to train investigators to use the FVSA, said the system had been in use in Malaysia since 2007, but he was not allowed to disclose his clients.

He did, however, reveal that the FVSA was used successfully in interviews on terror suspects in the Sabah intrusion.

"It was used to identify those involved and absolve the innocent with 100% success," he said, adding that he only learnt about this from a local analyst in August.

The website of International Truth Verification Technologies, which produces the FVSA, has indirect references to several local agencies.

"It's also being used in Singapore, in the US, Colombia, South Africa, the Philippines and Brunei," Ryan said, adding that the Central Intelligence Agency, under fire for torturing suspects in the so-called War on Terror, would have achieved more and preserved their reputation if it had used the FVSA.

Ryan, who did a short stint in Vietnam as a civilian contractor before being wounded in the late 1960s, said he witnessed the brutal interrogation of Viet Cong prisoners.

Besides interrogation, the FVSA is being used for border security and recruitment of top executives.

Ryan said he developed the FVSA because earlier lie detectors, including the polygraph and Voice Stress Analysis, were inconclusive at best, but were still being used by agencies around the world.

"That used to irritate me. If they are not conclusive, why bother?"

Ryan said the polygraph cannot be used on someone who had one beer, women who were pregnant and the underage, unlike the FVSA.