The AFP and customs intercept hundreds of tonnes of narcotics every year. But, the techniques of criminals and smugglers are becoming more complex, and unfortunately, more effective.

Nigel Phair is a former Australian Federal Police Officer who took on a range of high profile drug importation cases. This saw him intercepting large quantities of drugs, investigating its origin and surveilling its eventual destination in Australia.

Understand this work and hear Nigel walk host Brent Sanders through how the police undertake these investigations and how things have changed over the years.

If this content affected you, the number for LifeLine is 13 11 14.

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It took 37 years, a failed murder trial, and an Australian mathematician to finally prosecute one of Scotland's most infamous serial killers.

Professor David Balding is a pioneer in the field of mathematical computational genetics. Join host Kathryn Fox and hear how using things like probability, David can calculate the likelihood of DNA belonging to offenders, victims and crime scenes.

If you or someone you know is experiencing, or at risk of experiencing, domestic, family or sexual violence, call 1800RESPECT on 1800 737 732, text 0458 737 732 or visit 1800RESPECT.org.au for online chat and video call services.

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The gangs of New Zealand are like nothing else, and as an undercover cop, you're forced to prove yourself, demonstrate you're a criminal and show you're capable of committing violent and often deadly crimes.

That was the life of undercover operative Mark Van Lee Warden, who spent years as a covert officer deep inside the underworld of the New Zealand ganglands. He was required to tackle some of the country's most powerful underworld figures, including the infamous convicted murderer Ricki Goodin. Mark sat down with host Brent Sanders to explain how he became an undercover cop, and the impact it had on him in his professional and personal life.

To hear more about Mark's time in the force, his book is available here.

Mark's work post policing at Warden Consulting.

This episode features references to mens violence against women, if this content affects you, help is available via LifeLine on 13 11 14, or, dial 1800 RESPECT on 1800 737 732.

See omnystudio.com/listener for privacy information.