On Monday, 4th District Court Judge Claudia Laycock ordered the three terms to run consecutively to one another.
Between Oct. 20 and 26, Gray stabbed the victim more than 40 times with five different knives at the trailer home they shared, including cutting her throat, stabbing her in the genitals and cutting off one of her breasts, according to charging documents and information from Deputy Utah County Attorney Julia Thomas.
Thomas called the case "really gruesome," and said Gray was a "very dangerous man."
Gray eventually dragged the victim's body to a bathroom, where he covered it with cleaning chemicals to prevent decay or odor, according to charges.
Gray then removed the clothing he wore while committing the crime, removed jewelry from the victim's body and partially cleaned the scene, charges state. He also attempted to seclude the body by securing doors and windows with ropes and other means.
Gray then fled to Yakima, Wash., where he confessed the crime to police.
Court documents indicate that on Oct. 26, Gray walked into the Yakima police station and asked to speak to an officer for whom he was once an informant.
Gray told the officer he had awakened from a "drug-induced sleep," to find Brackenbury dead from multiple stab wounds to the chest.
Based on that information, Orem police officers entered the trailer home and found the victim.
Later the same day, Gray confessed to Yakima police that he was the person who had stabbed Brackenbury and mutilated her body, court documents state.
Thomas said Gray has a history of domestic violence. A search of Utah court records show Gray's only other criminal conviction was for DUI in 2010.