A CNN television anchor, known for her aggressive on-air questioning, has been dragged into a story she was pursuing after one of her guests committed suicide shortly before an interview was broadcast.

Nancy Grace, whose eponymous, nightly programme describes itself as "television's only justice themed / interview / debate show" has refused to accept any responsibility for the death of Melinda Duckett, a 21-year-old woman who shot herself after being interviewed by Grace, a former criminal prosecutor, about the disappearance of her two-year-old son.

Grace banged her desk and asked Duckett repeatedly about her whereabouts on the day her son, Trenton, vanished in an interview recorded on September 7. By the time the footage was broadcast the next day, Duckett had killed herself with her grandfather's gun.

Grace, who boasted a 100 per cent success rate in almost 100 trials as a prosecutor for Atlanta Fulton County in the 1990s, told her audience on Monday that she did not feel responsible for her guest's death and that her line of questioning was similar to that taken by the police.

"I do not feel that our show is to blame for what happened to Melinda Duckett," said Grace, one of a clutch of American cable news presenters who host magazine-style shows that cover the country's most serious and sensational crimes. "The truth... is not always nice or polite or easy to go down. Sometimes it's harsh, and it hurts."

Duckett reported her son missing to police on the evening of August 27 after she finished watching the film Lock, Stock and Two Smoking Barrels and returned to find his bed empty and a 10in slit in a window screen in his room.

By the time she was questioned by Grace, she had posted fliers at petrol stations around the town of Leesburg, Florida, and been interviewed by the police and the FBI.

But under determined interrogation from the talk show host, she became confused about whether she had taken a polygraph test and declined to give precise details of her movements on the last afternoon she spent with her son.

After being asked several times why she wasn't sharing more details with Grace, Duckett said that she had been told not to give more information and alluded to a difficult relationship with the local press.

"I'm not going to put those kind of details out," she said.

"Why?" Asked Grace.

"Because I was told not to."

"Ms Duckett, you are not telling us for a reason. What is the reason? You refuse to give even the simplest facts of where you were with your son before he went missing. It is day 12," said Grace, who then allowed Duckett a jumbled reply before cutting to a media pyschologist:

"Let's go to Dr Lillian Glass, psychologist," a transcript from the show reads. "Weak spots?"

"This doesn`t make any sense to me," said Dr Glass. "And the fact that she's skirting around the issue and can`t get to the point concerns me a lot. Her reaction is not the typical reaction of a mother who has a missing child."

Police have not named Duckett as a suspect in the disappearance of her son but are focusing more closely on her movements in the last hours they are believed to have spent together.

Her family have blamed her suicide on the stress surrounding the incident, the recent loss of her job and her exposure to a hungry media.

"Nancy Grace and the others, they just bashed her to the end," Duckett's grandfather Bill Eubank told The Orlando Sentinel yesterday.

"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 programme 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," the statement said.

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