Season 1: Episode 12 - Butterfly Effect

Butterfly Effect: ­A young ironworker is found murdered at his construction site. The victim was a stellar student from a blue-collar background and had put off attending college to help his family through rough times. But the investigation will put the victim's reputation to the test as the team probes the underbelly of the construction business, examining his possible involvement in a robbery ring and links to the mob. It’s only through Carrie’s persistence and memory that they uncover his knowledge of a major structural flaw in the building that explains the murder.