The sordid revelation emerged on the basis of a fresh DNA report, the police officials said adding that the girl's elder uncle too had allegedly exploited her and was arrested.
The girl's elder uncle's DNA sample did not match that of the newborn following which the suspicion fell on his younger brother who too had been accused of rape by the survivor, they said.
"The DNA sample of the younger maternal uncle of the girl has matched with that of the baby of the girl," senior Chandigarh police officer Jagdale Nilambari Vijay, said this evening. She maintained that both the girl's uncles had sexually exploited her.
"A supplementary charge sheet has been filed before the court of Additional District and Sessions Judge, Poonam R Joshi, here today," the police officer said.
The rape survivor, whose abortion plea was turned down by the Supreme Court, had in August delivered a baby through C- section at a government hospital in Chandigarh.
The crime came to light when the girl was taken to a hospital after she complained of stomach ache in July where she was found to be over 30 weeks pregnant.
On July 28, the Supreme Court had dismissed a plea seeking its nod for terminating the 32-week-old pregnancy of the rape survivor after taking note of a medical report that abortion was neither good for the girl nor for the foetus.
The Supreme Court bench had taken note of the report of the medical board set up by Post-Graduate Institute of Medical Education and Research, Chandigarh, which was set up on the directions of the apex court, to examine the rape survivor and the consequences if the termination of pregnancy was allowed.
Get the latest election news, live updates and election schedule for Lok Sabha Elections 2019 on ndtv.com/elections. Like us on Facebook or follow us on Twitter and Instagram for updates from each of the 543 parliamentary seats for the 2019 Indian general elections.