Before it was over, CNN's Grace was pounding her desk and loudly demanding to know: "Where were you? Why aren't you telling us where you were that day?"
A day after the taping, Duckett, 21, shot herself to death, deepening the mystery of what happened to the boy.
Police have refused to say whether she left a suicide note, and said nothing they have found so far in their investigation of her death has shed light on the whereabouts of her 2-year-old son, Trenton.
Investigators have stopped short of calling her a suspect but have focused increasing attention on her movements just before the boy vanished and the notes, computer, camera and other items seized from her house.
Duckett's family members disputed any suggestion that she hurt her son. They said that the strain of her son's disappearance pushed her to the brink, and the media sent her over the edge.
"Nancy Grace and the others, they just bashed her to the end," Duckett's grandfather Bill Eubank said. "She wasn't one anyone ever would have thought of to do something like this. She and that baby just loved each other, couldn't get away from each other. She wouldn't hurt a bug."
Janine Iamunno, a spokeswoman for Grace, said in an e-mail that Duckett's death was "an extremely sad development," but that the program would continue covering the case.
"We feel a responsibility to bring attention to this case in the hopes of helping find Trenton Duckett, who remains missing," Iamunno said.
Duckett had told police that after she finished watching a movie Aug. 27, she went to check on Trenton in his bedroom, and all she found was an empty crib — and a 10-inch cut in the window screen above it.
At the time, she was living with her son, wading through a messy divorce with the boy's father and trying to get her life back on track after getting laid off from her job with a lawn care company.
The boy's disappearance in this town of 19,000 people about 45 miles northwest of Orlando stretched the 75-member police force to its limits. Fliers were posted on gas station doors around town, asking for information from anyone who might have seen the boy, a brown-haired youngster wearing denim shorts and a diaper.
Trenton's father, 21-year-old Josh Duckett, was closely questioned after the boy disappeared. Newspapers reported that his wife had taken out a temporary restraining order against him. But Josh Duckett took a polygraph test and has answered all police questions satisfactorily, Capt. Ginny Padgett said.
On Sept. 7, Melinda Duckett gave a telephone interview to CNN Headline News' Grace, a former prosecutor known for practically cross-examining her guests. Duckett stumbled over such questions as whether she had taken a polygraph — she said she refused on the advice of her divorce lawyer — and where, exactly, she was shopping with the boy before his disappearance.
Hours before the interview aired, Duckett shot herself Friday with her grandfather's gun at her grandparents' house, up the road from where she was living.
Investigators are still trying to piece together a timeline of where she and Trenton were 24 hours before she reported him missing. On Tuesday, they released the make and model of her car, a 2000 Mitsubishi Eclipse, and asked anyone who might have seen it during that period to call them.
Also on Tuesday, a newspaper reported that she bought a shotgun from a pawn shop two days before Trenton vanished. Padgett said police could not confirm that.
On Monday, agents used dogs and digging equipment to search an outlying area that someone had called about, but found nothing. Investigators continued to field tips.
"We're following up," Padgett said. "Hopefully they'll bring in something to help us firm up the timeline."