She ran away with her boyfriend a month ago and refused to return to her home village when they got married.
When pressed to explain why on an Indian TV talk show, the 16-year-old shocked viewers and the host, reported British paper Daily Mail.
The girl, who has not been identified, tearfully said on the live programme in Chennai, India, that her father was a triple murderer.
She said he had poisoned a neighbour, his 20-year-old daughter and his son-in-law, 22, in a dispute over jewellery.
Following her claims, police later went to the parents' home and found three bodies buried in the backyard.
Producers of the Zee Tamil channel show, Solvathellam Unmai, had invited the teen to appear to talk about how she had eloped with her 21-year-old boyfriend.
Her father, identified only as Mr A. Murugan, and mother, Madam Rajeswari, were in the studio when the teen made her startling accusation.
The three had been constantly arguing in the studio when host Nirmala Periyasamy suggested that they make amends and go home together.
Said Ms Nirmala: "The girl was constantly telling us that she was afraid of her father as he may murder her and her husband.
"When I repeatedly questioned her, the girl broke down and told us that her father had murdered three persons in their house in 2008."
As the reality show ended, the family members were still arguing. Mr Murugan and his wife then left to return to their village on their own.
But police said the father was furious with his wife for backing up their daughter's claims on TV. Said an officer: "He abused his wife on the bus going back to their village."
Mr Murugan later got off the bus before it reached the village, telling his wife she would never see him alive again.
Police said the neighbours had left gold jewellery with Mr Murugan for safekeeping, but when they asked for it to be returned, he refused.
Said Deputy Police Superintendent Gopal Sekar: "He decided to eliminate them and keep the gold. "So he gave them food laced with poison and then buried them in his backyard."
A police manhunt is now on for Mr Murugan.
"We would never have known about these murders if the girl had not spoken about them on the TV show," said Supt Sekar.
Police have praised the teenager for her courage in naming her father as a murderer.
This article was first published in The New Paper.