He faces up to 15 years in prison on each count when he is sentenced May 20 by Judge John Morris.
Davis County Attorney Troy Rawlings said Monday afternoon that prosecutors will recommend to the judge that Nance serve the sentences consecutively, and they will recommend to the parole board that he serve all 30 years of his sentence.
Rawlings said the plea deal was offered because after his office reviewed the facts of the case, they felt a jury would likely have found Nance guilty on the lesser charge of manslaughter.
"We truly believe this is what a jury would have done," he said.
Rawlings said issues that played into the plea deal, including mental health issues and an imperfect self-defense claim that could have been used at trial, will be discussed during Nance's sentencing.
Nance killed his father at the Far West Motel, 410 N. Main St., on March 19, 2011.
Police have said the son confronted his father about a fight the older man had with Joseph Nance's mother.
"There was a domestic dispute between the suspect's parents," Kaysville police Capt. Brent Ward said at the time. "His mother and father were currently divorced, but they had been living together at a motel for the last month or two and had gotten into a domestic dispute."
Joseph Nance told police he shot his father in self-defense, according to court documents.
Police said that after Joseph Nance shot his father, he ran into a wooded area near the motel and was later picked up by some friends who did not know a shooting had occurred.
Officers found Nance hiding in a wooden bunker near Layton the next morning.