SKIATOOK, Okla. (AP) — A 19-year-old man has been arrested in connection with the stabbing deaths of his sister and their great-grandmother.

Michael Devin Stanley was booked into the Osage County Jail on a first-degree murder complaint Tuesday evening, according to a story published Wednesday in The Tulsa World (http://bit.ly/1exg3cL ).

Authorities say 74-year-old Esther Driskell was found stabbed to death in her Skiatook home about 5 p.m. Monday. Osage County Sheriff's Chief Deputy Charlie Cartwright says a 16-year-old girl was found dead with multiple stab wounds to the upper torso in a van on Tuesday. Authorities have not released the girl's identity, though family and friends identified her as Larisa Fraley.

Court records show Stanley is Driskell's great-grandson and Fraley's brother. It's unclear if Driskell has an attorney.

Skiatook police Detective Shane Thompson said Driskell owned the van, which helped officers determine the two deaths were related.

Shaylee Lewallen, Driskell's granddaughter, said she regularly played with Fraley when they were children and that Driskell routinely was a part of family vacations at Spring Creek.

A friend of Fraley's, Sara Herzler, said the teen was a beautiful person and a trustworthy friend, despite having a difficult family life.

"I couldn't believe it," Herzler said. "I saw the news report and read the details, then I lost it. I still can't grasp that it really happened."