The boy's father, Jeremy Roberts, had the boy make the call, police said, after allegedly stabbing his ex-wife to death outside his apartment.
Roberts then calmly got on the phone himself, giving the apartment's address and informing police that the "only" weapon -- a knife -- was outside with his ex-wife, Candice Roberts.
"What did you do?" the dispatcher asks him.
"She's covered in a blanket. You guys will see," Roberts responds in an even tone.
He can then be heard, on the nearly five-minute 911 call, telling his children that they have a "good big sister (who) will take care of you guys."
"I told you that there's a lot of things that you don't understand, and you don't know. And now there's no choice for them to come out," Roberts said in the recorded call, without detailing what he meant.
Before going to the front door -- and handing the phone back to his 13-year-old son -- Roberts says, "One more hug. I love you guys." A small child can be heard crying in the background.
The 13-year-old boy can be overheard telling his father, "I don't want to see you right now."
Roberts, 38, is in custody and will be charged with murder in connection with his ex-wife's death, police said.