Analyzing the ink and pressure of the messages left at crime scenes.

"I-15 Murders" is the 11th episode of the first season of CSI: Crime Scene Investigation . It originally aired on January 12, 2001. 🔎 Episode Overview

Used to find biological fluids and prints in public spaces like the grocery store. 👥 Character Development

Gil Grissom and Catherine Willows investigate the death of a woman found in a grocery store restroom.

Sara Sidle and Warrick Brown investigate the death of a man found in his home, which initially looks like a burglary gone wrong but reveals a more domestic motive.

This episode reinforces Grissom's dedication to "following the evidence" even when the scale of the crimes begins to feel overwhelming.

The killer leaves a specific "signature"—writing on the bathroom stall—which suggests a serial predator.