It happened at a home on Morgan Drive near Stonehill Drive just south of U.S. Highway 64. The area is east of Zebulon - near the Wake County line, in a normally quiet corner of Franklin County.
Franklin County Sheriff's Office Chief of Staff Terry Wright said 18-year-old Oliver Mauricio Funes Machada called 911 himself around 12:45 p.m. Monday and was still on the scene when deputies arrived.
After calling 911, the 18-year-old suspect walked out of the house holding his mother's head in one hand and what appeared to be a large knife in the other, according to authorities.
"It looked to be a large butcher knife, the weapon that was used." said Sheriff Kent Winstead.
The teen - who was taken into custody without incident - is charged with first-degree murder.
Federal officials also said Tuesday that Machada is in the country illegally and they've issued an immigration detainer for him.
Deputies said they found 35-year-old Yesenia Funez Beatriz Machado dead inside the home. Two young girls found in the home were unharmed. A fourth child was at school when the incident happened.
"I can't tell you how many stab wounds or cuts, Winstead said. "We just haven't gotten that far in the investigation."
Analysis of the crime scene was delayed by a couple hours because Sheriff's deputies had to go to a neighboring county to get a search warrant. Winstead said a judge signed the order around 4:15 in the afternoon.
"We'll be here as long as it takes to do a thorough search. We owe it to the victims to make sure it's done in a proper manner - To make sure once it gets to the courthouse, justice can be served," said Wright.
Authorities removed the mother's body from the home about 8:30, and investigators cleared the scene shortly before 10 p.m.
At this point, investigators have few answers as to what led to this family tragedy.
"It's uh, hard to comprehend," said Eddie Garner, a neighbor who lives a few doors down from where crime investigators were documenting every inch of the unthinkable.
Garner was there as the victim's husband arrived home Monday afternoon to the devastating scene.
"I don't know what they told him," Garner said. "I mean, we just heard him crying and you could hear him all over the place. I mean he definitely never expected something like this to happen."
Funes Machada made a first court appearance Tuesday where he was ordered held without bond.
The Associated Press contributed to this report.