Tiffani Hill, 31, her husband, John Donato, 42, and daughter, Leanne, 1, were all discovered deceased on July 30.
It is believed that the husband committed the act in an apparent murder-suicide in Oklahoma.
Nine months prior to the deaths, Tiffani had won $2 million in the lottery.
All three had gunshot wounds to the head, but the little girl was still breathing when officers got to the location. She was taken taken to a hospital in Texas where she succumbed to her injuries.
The woman had wed Donato after winning the money. An attorney for Hill’s family noted that problems arose after receiving the funds.
Three children were in the residence at the time but were not hurt. The leftover money will be used to care for them.
The FBI is in control of the case because it transpired on tribal property. Hill was a part of the Choctaw Nation.