Report issued on India girls' hanging

• NEW: No stress marks or male DNA were found on the girls' bodies, an official says


• An investigation finds that the two girls, who were cousins, committed suicide


• There is no evidence of rape, sexual assault or murder, the investigators say


• An initial report had found the girls were raped and strangled, but it was later questioned

New Delhi (CNN) -- An investigation into the deaths of two teenage girls found hanging from a mango tree in northern India has concluded that they committed suicide and that there's no evidence of rape, sexual assault or murder, according to a report released by India's Central Bureau of Investigation on Thursday.

The two girls, who were cousins, were found dead in May in a remote village in the Badaun district of Uttar Pradesh state.

During the initial stages of the investigation, an autopsy report confirmed the two girls had been raped and strangled.

The teenagers' families filed a complaint accusing a group of men of rape and murder. But forensic reports commissioned by federal investigators subsequently said the girls were not raped, and charges against the men were dropped.

The case caused widespread revulsion in India and beyond, especially after the brutal gang rape of a girl on a public bus in New Delhi in December 2012.

That incident energized activists and women generally, with government officials promising action to ensure that girls and women feel safe.

Law enforcement agency: No male DNA found

The findings of the investigation in the Uttar Pradesh case were outlined at a news conference Thursday.

Kanchan Prasad, a spokeswoman for Central Bureau of Investigation, said they were based on about 40 scientific reports.

Investigators found no stress marks or traces of semen on either of the bodies, and no trace of male DNA was found on the girls' clothes or anywhere on their bodies, she said.

The report will be submitted to Badaun Court next week, she said, and there will be no further investigation by the CBI.

All five of the accused men were released on bail after the decision not to file charges, and they remain on bail. The court will decide whether it will take the case forward.

Lie-detector tests were conducted on the accused and the relatives. While the results of the accused were fine, those of the relatives indicated deception, she said.

A top-level CBI official, who took questions from journalists but declined to be named, said it was "medically proven that it was a suicide."

Forensic experts also had determined that the mango tree from which the girls were found hanging was the easiest in the grove to climb and that the girls would have been able to do so, he said.

Family pressure suggested

Asked about the discrepancy between the initial autopsy and subsequent forensic reports, the official said that the investigators involved in the first autopsy report were not experts and had mistakenly concluded there had been a sexual assault.

The investigators did not know why the girls had committed suicide but suggested it might be because the elder girl was under pressure from her family over a relationship with a man from a different caste -- who was one of those accused in the case.

"Her family didn't approve of this and she was under pressure. Being an immature girl living in a very conservative part of India, it must have been hard for her," the official said.

It's not known why the younger girl would also have killed herself in this case, but the two cousins were very close, he added.

CNN's Laura Smith-Spark and Kunal Sehgal contributed to this report.