FORT DODGE, Iowa (AP) — Prosecutors have called their star witness in the first-degree murder trial of a woman who claims she killed an Iowa neighbor in self-defense: a former friend who supported her but came forward a decade later to provide key evidence.Farmer Mary Higgins testified Friday at the trial of Tracey Richter in the 2001 death of 20-year-old Dustin Wehde at her home in Early, a small town in northwest Iowa. Richter claims she shot Wehde after he broke into her home.Higgins says Richter showed no emotion when she recounted the events "like she was telling me her grocery list." She also says Richter told her about a pink spiral notebook claiming her ex-husband was behind the attack.Investigators say they kept the notebook's existence a secret.