LOUISBURG, N.C. — An 18-year-old man accused of decapitating his mother promised an emergency dispatcher that he wouldn’t kill two young siblings heard wailing in the background of his 911 call, according to a recording released Thursday.

The suspect, who called 911 not long after the killing Monday afternoon, calmly gave answers throughout the nearly 17-minute recording — with responses ranging from his location to the names of his 4-year-old sister and 2-year-old brother, who were in the house. He said his father was away and recited the man’s name and cellphone number in an even tone. The dispatcher asked repeatedly about the children.

“I’m not going to kill them; don’t worry,” the suspect responded.

The siblings were found unharmed when deputies arrived Monday at the house in Zebulon, about 30 miles east of Raleigh. Court documents said the first deputy on the scene saw the suspect walk out of the house carrying a knife in one hand and his mother’s severed head in the other.

The emergency call began with the suspect saying he killed someone and the dispatcher asking him why.

“Why did you kill somebody?” the dispatcher says.

“Because I felt like it,” the suspect answers.

Later, the dispatcher asked if the mother had made him mad: “What was she doing? Did she make you mad, or what happened?”

The suspect responds: “Yes, she made me mad.”

The recording offered chilling details of the aftermath of the killing by the suspect described by his defense attorney as mentally disturbed. As they trade questions and answers, the dispatcher sounds unnerved at times. When he says he stabbed his mother eight times, the dispatcher responds: “Oh, mercy.”

The exact spelling of the suspect’s name was unclear. Local court records listed him as Oliver Funes Machada, federal records as Oliver Funes Machado. He is charged with first-degree murder.

The mother’s name, according to local authorities who received the information from a 14-year-old son, is Yesenia Beatriz Funez Machado, 35.

The suspect was from Honduras and in the US illegally, said US Immigration and Customs Enforcement spokesman Bryan Cox.

The prosecutor said officials were seeking a mental evaluation of the suspect, and that his apparent mental issues could delay uncovering a motive for weeks or months. The warrants say he was on four medications for a psychiatric condition, but don’t elaborate.

His public defender, attorney C. Boyd Sturges III, has said he spoke to the man and that he is profoundly mentally disturbed.

The suspect’s next court appearance is scheduled for Tuesday.