Police said the autopsy report of the girl has revealed that she died due to stabbing.
"Rape has been ruled out in the case," they said.
The body, which was recovered yesterday, remained unidentified for hours. It was identified after the girl's parents were traced through the missing person report lodged by them about the girl.
"The girl's parents said she had left home for some work on Wednesday (September 10) and did not return after that. They had searched for her before filing the missing report with police," Additional Commissioner of Police (New Delhi district) SBS Tyagi said.
The park is located in the backyard of the Presidential Palace.