October 1985, 17-year-old Missy Avila goes for a walk in the Angeles National Forest,

with two of her closest friends.

Three days later, hikers find her body face down in a creek, waded down by a massive log.

What makes this case absolutely unforgettable is what happens next.

One of the girls who killed her moved into

Missy's family home, lived there for a time, comforted Missy's mom, helped them search for the

killer, all while knowing exactly what happened. This is the story of Michelle Avila. October 1985, October 1985 in the San Fernando Valley.

Missy Avila was 17 years old, a junior at San Fernando High School.

She's tiny.

Four foot 10, 97 pounds.

She's got long brown hair that goes all the way down to her waist. She's got two childhood

friends named Karen Severson and Laura Doyle. These girls have known each other since they were

eight years old. That's almost a decade of friendship, sleepovers, secrets, all of it. Somewhere along

the way, things started to change. High school happened.

With high school came all the complicated stuff that can turn friendship into something different.

Karen Severson started to resent Missy. The reasons sound almost trivial when you say them out

loud, and they were very real to a teenage girl. Missy was popular. Missy was pretty, getting attention from boys.

As Missy got older, she started spending less and less time with Karen and more time dating,

going to parties, doing normal high school stuff. Karen didn't handle this well. She started spreading

rumors about Missy, vicious rumors that Missy was sleeping around

with different guys. These were more than whispers in the hallway. These rumors got so bad,

at one point, a group of girls physically attacked Missy because they believed Karen's

...