Who is Glenn and Rachel Linton from Sweet and Deadly and what is their importance?

Glenn and Rachel Linton were Catherine's parents. They were killed in a car accident while on their way to visit her. It is later discovered that someone had tampered with their car, causing their deaths, and afterward, Catherine sinks into a deep depression. Six months later, the death of Leona, the possibility of love, and the hope of finding the killer force Catherine out of her depression. She begins to investigate Leona's death, and in the process, realizes that her father had a connection to the killer.