The violent deaths of four teenagers in an Austin yogurt shop in 1991 forever changed the city, and Austin’s collective trauma is on full display in a new HBO documentary series, “The Yogurt Shop Murders.” Over the years, detectives have tried to find the killers, and two people were even convicted – but later released after being cleared by DNA. Still unsolved, the killings of Amy Ayers, 13; Eliza Thomas, 17; and sisters Jennifer Harbison, 17, and Sarah Harbison, 15, rocked the teenage years of host Nikki DaVaughn, she shares in today’s episode with the series’ director, Margaret Brown. The first episode is out now, and three more will be released in the coming weeks