ZEBULON, N.C. -- The North Carolina teenager accused of beheading his mother Monday afternoon told dispatchers he killed the woman “because I felt like it,” according to an investigator’s affidavit obtained by CBS affiliate WNCN.

The 18-year-old also told a dispatcher that “he stabbed her ‘like eight times’ and left the knife in her mouth,” according to the sworn statement by Det. A.R. Roberts of the Franklin County Sheriff’s Office, reports the station. The first deputy to respond to the suburban Raleigh home found the teen walking outside carrying a knife in one hand and a severed head in the other, documents say.

Oliver Funes Machada in a North Carolina court Tuesday, March 7, 2017 WNCN

The teen’s 4-year-old sister and 2-year-old brother were in the house, the statement says. They were unharmed.

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The exact names of the suspect and his mother were unclear. Local court records list the suspect’s name as Oliver Funes Machada. Federal records list the teen suspect’s name as Oliver Funes Machado, said U.S. Immigration and Customs Enforcement spokesman Bryan Cox. In a statement, Cox said the suspect was from Honduras and was in the country illegally.

Franklin County Chief Sheriff’s Deputy Terry Wright gave the mother’s name as Yesenia Beatriz Funez Machado, citing a spelling given to authorities by her 14-year-old son.

Funes Machada was charged Monday with first-degree murder after he called 911 to say he had killed his mother, according to a Franklin County Sheriff’s Office statement. He was reportedly speaking on the phone with dispatchers until police arrived. It said he was arrested without offering resistance, and that the decapitated body of his 35-year-old mother was found inside.

According to a search warrant obtained by the station, investigators also found bloody shoeprints, a “large kitchen knife with apparent blood,” and bloody clothing in a laundry hamper, including sweatpants, a t-shirt and a onesie.

Funes Machada’s public defender, Louisburg attorney C. Boyd Sturges III, said in a phone interview that he spoke with Funes Machada for an hour in the Franklin County jail.

“It does appear there’s some substantial mental health issues involved in this case,” Sturges said. “I’m not a doctor, so I can’t really elaborate. He’s a pretty profoundly disturbed young man in a mental health kind of way.”

Investigators also seized medication belonging to Funes Machada. In court, officials said that medication was used to treat psychosis and schizophrenia, the station reports.

District Attorney Mike Waters said officials were seeking a mental evaluation of Funes Machada. Due to the suspect’s apparent mental state, Waters said, “this is something that’s going to take weeks and months for us to get some answers as to why this happened.”

The district attorney said the suspect was being transferred to Central Prison in Raleigh and his next court appearance was set for March 14.

A fourth child was in school at the time of the attack. Neighbor Randy Mullins said he believes all the other children were the suspect’s siblings.

The homicide scene in Zebulon, N.C. where officials say Oliver Funes Machada, right, decapitated his mother March 6, 2016 WNCN

Mullins was leaving his house minutes after the first deputy arrived and he said he saw the woman’s head lying in the front yard about five feet from the porch. The deputy appeared to have just handcuffed the suspect and seemed rattled when Mullins approached to ask if he needed help.

“You could see in his face he had a lot of concern. I’m not saying he was scared, but you could tell he was concerned,” Mullins said of the deputy.

Mullins then went back to his house across the street and told his 91-year-old mother to stay inside. He said a half-dozen more law enforcement vehicles arrived within minutes and a deputy covered the woman’s head.

“I couldn’t believe it. Things like that don’t happen,” said Mullins, 59, who has lived in the neighborhood for 25 years. “You can’t believe somebody would do that. You hear about that, but it never happens across the street from you.”

He added the suspect appeared calm while he sat handcuffed as a deputy kneeled down to comfort the two younger children. “He was sitting there like he didn’t have a care in the world,” Mullins said of the 18-year-old. “He didn’t appear to be upset; he didn’t appear to be crying.”

Mullins said the family had moved in around June 2016. He didn’t know them well, but he and his mother said they seemed friendly.

“If they were outside, they always waved at you,” said Clearsy Mullins, who’s been living with her son for about 10 years.

On Tuesday, a group of friends or relatives went to the house where the woman was killed, loading belongings including a stroller into two minivans. A neighbor who had stopped by to offer his condolences told a reporter the group didn’t want to talk, and they left after about 20 minutes.