The podcast episodes provided discuss several investigation techniques used in different types of cases, including true crime and missing persons investigations.

For example, the episode '#495 - Turning A Husband Into Flowers - Lopez Island, Washington' from the 'Small Town Murder' podcast examines the use of luminol testing and concrete testing to uncover evidence in the 1980 disappearance of sea captain Rolf Neslund.

Similarly, the episode 'S4E8: Back To Nome' from 'Up and Vanished' discusses various techniques used in investigating the disappearances of Florence Okpialik and Joseph Balderas in Nome, Alaska, such as installing a tip line, following up on credit card activity, and interviewing family members and authorities.

The episode '#249: The "K-Pop Serial Killer" - "Handsome" Killer Stirs Online Discourse & Shocks South Korea' from 'Rotten Mango' provides insights into the investigative techniques employed by the police in the case of alleged South Korean serial killer Lee Gi-young, including tracking CCTV footage, following financial trails, and conducting psychological evaluations.