Diatoms are a group of unicellular algae that have been recorded and classified for over 200 years and have been used in a range of applications in forensic science. We have developed a quantitative diatom-based reconstruction technique to confirm drowning as a cause of death and localize the site of drowning in two recent, high-profile, case studies. In both case studies we collected diatom samples from the local and/or regional area to act as a control in the examination of diatom assemblages associated with lungs and clothing. In Case Study 1 the modern analog technique suggested that all lung and clothing samples have statistically significant similarities to control samples from shallow water habitats. In Case Study 2, the analog matching suggested that the majority of lung samples show a statistically significant relationship to samples from a pond, indicating that this was the drowning medium.