Authorities in Oklahoma have arrested and charged four people on suspicion of kidnapping and murder in connection with the March disappearance of two Kansas mothers, who were last seen driving through the Oklahoma panhandle last month.

The Oklahoma State Bureau of Investigation announced that Tad Bert Cullum, 43, Tifany Machel Adams, 54, Cole Earl Twombly, 50, and Cora Twombly, 44, were taken into custody on Saturday; they are suspected of kidnapping and murdering Veronica Butler, 27, and Jilian Kelley, 39, before they vanished on March 30. The four were booked into the Texas County Jail in Oklahoma on suspicion of first-degree murder, kidnapping and conspiracy to commit murder. Adams is the grandmother of Butler’s children, and Cullum is her boyfriend; while Cole and Cora Twombly have been in an eight-year relationship and are friends with Adams on Facebook.

Butler and Kelley were the subjects of an “endangered missing advisory” issued by Texas County authorities on March 30 after a vehicle they were traveling in was found abandoned in a rural part of Texas County south of Elkhart, Kansas, the bureau said. The women were only reported missing when the car they were driving was found 1,000 feet off Oklahoma State Highway 95, approximately 3 miles away from its destination. Butler and Kelley were considered acquaintances, as Kelley supervised Butler’s visits with her children. The women were traveling to Eva, Okla. to pick up Butler’s children who have been living with their paternal grandfather, according to NewsNation.

Butler and Kelley have yet to be found; Butler was in the middle of a bitter custody battle with the father of her children, seeking more visitation time, as she sought full custody of the children. KFOR reported that Adams is said to have had custody of the children at the time of Butler’s disappearance.

Anyone with information about the whereabouts of the women is asked to contact the Oklahoma State Bureau of Investigation at tips@osbi.ok.gov or 1-800-522-8017.

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