Michael Devin Stanley, 19, is facing charges of first-degree murder in Tulsa and Osage counties for the deaths of his great-grandmother, Esther Driskell, 74, and half-sister, Larisa Fraley, 16, the Tulsa (Okla.) World reported.
Driskell was found dead in her Tulsa County home on the evening of Jan. 27. A medical examiner said she suffered seven stab wounds to her chest and body, said an affidavit from a Skiatook, Okla., detective.
Fraley was found the next day in Osage County.
Police arrested Stanley on Jan. 29 and during questioning he allegedly admitted to stabbing Driskell and Fraley with a paring knife, the affidavit said.
Stanley "stated that Driskell had been on him about 'things' and had been asking for him to do the dishes," the detective said.
The suspect allegedly told detectives he stabbed his great-grandmother before leaving her home with his sister. He then stabbed Fraley after she told her brother "he could not keep her with him forever like he wanted to," the affidavit said.
Stanley is scheduled to appear in Osage County District Court on Friday.