In October 2018, sixteen year old Karlie Lain Guse disappeared from a small community in Mono County, California. She was last seen near her home in White Mountain Estates, walking toward Highway 6 in the early morning cold.
Karlie lived with her father, Zac, her stepmother, Melissa, and younger siblings. She attended Bishop Union High School, spent time with friends, and, according to family, had ordinary teenage conflicts but no history of long term runaway behaviour.
On the evening of 12 October 2018, Karlie went to a small gathering with friends. She smoked marijuana and soon felt extremely unwell and frightened, enough that she called Melissa and asked to be picked up and taken home.
During the drive back, Melissa later said that Karlie seemed paranoid and believed a car was following them. Once they reached the house, Karlie remained anxious and unsettled, cycling between calm and panic and saying she felt something very bad was going to happen.
At home, Melissa gave her a salad and tried to keep her focused. Karlie spat it out and said, “This the devil’s lettuce,” treating the ordinary food as if it were dangerous.
Out of concern, Melissa decided to record Karlie on her phone so they could play it back when she felt normal again. On the eight minute audio, Karlie says, “I really messed up today,” and Melissa answers, “We all do things in life that we regret, drugs especially.”
Karlie thanks her and says, “I love you.” Later in the same recording, when Melissa offers more salad, Karlie blurts, “This the devil’s lettuce,” repeating the strange phrase that has become one of the most discussed details in the case.
According to a detailed newspaper account, Karlie also refuses sleep during the recording. She says she does not want to go to sleep because she believes Melissa will kill her, and says she keeps thinking about demonic things and cannot stop.
The audio has never been released in full to the public, but journalists, television producers, and Karlie’s biological mother have heard it. People who have described it consistently say that Karlie sounds extremely frightened, confused, and paranoid throughout, while Melissa sounds controlled and tries to calm her.
That night, Melissa says she stayed with Karlie because she worried about her state. In her most consistent version, she lay beside Karlie in bed, saw her awake at around 5:30 in the morning, then drifted off again for a short time.
When Melissa woke again between about 7:00 and 7:30, Karlie was gone. The front door was unlocked. Karlie’s phone, glasses, and other belongings were still in the house, and there were no clear signs of a struggle inside the home.
The family reported her missing that morning. Three neighbours later told law enforcement they saw a girl who matched Karlie’s description walking south in the subdivision and near Highway 6, wearing a white shirt and dark pants without a jacket.
Those witnesses placed her about thirty yards east of Highway 6 and one hundred yards south of Sierra View Road. They did not report seeing a vehicle stop, any argument, or any obvious injury, only a thin teenage girl walking alone along the road.
The Mono County Sheriff’s Office and later the FBI organised extensive searches around White Mountain Estates and Highway 6. Teams used helicopters, off road vehicles, and dogs over several days, and later checked digital records from phones and social media for any sign of planning or contact.
Those efforts did not find clothing, remains, or verified evidence of where she went after the last reported sighting. Periodic tips and claimed sightings in other towns and states were checked and did not result in a confirmed location or suspect.
Inside the family, Karlie’s biological mother has said she believes her daughter may have died in or near the house after a bad drug reaction and that the full truth about the night has not been shared. Her father and stepmother say they told investigators everything and believe she walked away and encountered danger outside.
Those disagreements, combined with changing small details in media interviews, have driven years of public argument about the case. The sheriff has called much of it a “trial by social media” and has emphasised that the case is officially a missing person investigation, not a declared homicide.
In 2020, the FBI and Mono County Sheriff launched a twelve part video series titled “The Things They Carry,” where family members, witnesses, and investigators talk about Karlie and the effect of her disappearance. The public release of the audio itself came later on a television documentary.
As of 2025, Karlie remains missing from the high desert community where she was last seen. The FBI poster still lists her as last observed walking near Highway 6 on 13 October 2018, with all personal belongings left behind at home and no confirmed contact since that day.
