Larissa Lonehill, a 21-year-old Lakota woman, was last seen in Rapid City, South Dakota, on October 3, 2016. A member of the Lakota tribe who grew up on the Pine Ridge Reservation, she had been staying intermittently with her sister in Rapid City but had recently been asked to leave after a disagreement. On October 2 she visited her mother and was later picked up by her boyfriend. The next day she sent a text to a cousin saying she was with two male friends and on her way to a party; one of those men later told authorities he had dropped her off at that party but she was never heard from again.

Her family reported her missing soon after losing contact. Multiple agencies have been involved, and authorities have said they believe she is deceased and that her body may have been disposed of within a 100-mile radius of Rapid City; a reward was posted for information leading to an arrest and later updated to include information leading to the location of her body. No suspects have been publicly identified and little information has been released to protect the investigation.

If anyone knew Larissa, saw her on October 3, 2016, or has information about the men she was with or the party she was headed to, please come forward.