Stant also admitted that his actions felt "real" when he saw video of the aftermath of the attack.
Ashley Freeman and Lauria Bible, both 16, were last seen alive on Dec. 29, 1999, when the girls celebrated Ashley’s birthday with a sleepover at her Welch home.
An AMBER alert was issued Monday for 14-year-old Lilianais Victoria Cake Griffith and 7-year-old Luluvioletta Bandera-Magret.
Authorities are desperately searching for the daughters of a slain Texas mother whose roommate is believed to have the girls, police said.
Shanta Myers, 36, her 11-year-old son Jeremiah "JJ" Myers, her 5-year-old daughter Shanise Myers and Shanta's partner, 22-year-old Brandi Mells, were found dead on Tuesday