A tip to the Crimestoppers hotline in Sioux Falls led to the arrest Tuesday of 22-year old Allison Flora Armentrout of Sioux Falls and an unidentified 17-year old girl in connection with the April 22nd robbery of Cubby's gas station and convenience store at 49th & Western.

The clerk on duty that night was held up by four people wearing hooded sweatshirts and dark colored bandanas covering their faces, and carrying semi-automatic weapons. The clerk had told police that he thought they were 13 and 14 year old boys based on their height and voices.

The day after the robbery, Kelli Nicole Schlotterback, 19, and another unnamed 17-year-old girl turned themselves in after confessing the crime to their parents.

The trail for the other two people involved in the crime had gone cold until the anonymous tip came in.

The arrests closes the unusual case in that four females, two of them minors, were the only suspects involved. The motive for the crime is still unknown.