The girl had accused her friend of having taken her to the site of the incident, police said.
A girl was molested after being made to consume liquor by her friend and a 35-year-old man, police said on Saturday.
When asked whether the girl was raped, Lakhisarai Superintendent of Police, Kartikeya Sharma, said medical reports had not confirmed sexual assault.
The 35-year-old man Vinod Kumar, accused by the girl of molestation, has been charged under the POCSO Act.
Her friend has also been arrested and investigations were on to confirm whether she had consumed liquor as well, the police officer said.
The girl had accused her friend of having taken her to the site of the incident, police said.
The incident had taken place in Town police station area of the district on the intervening night of Thursday and Friday when the girl had gone out of her home to attend Durga Puja festivities.
She was found in a scantily-clad condition, near a three-storey building, causing bystanders to suspect that she had tried to commit suicide by jumping off the roof after being sexually assaulted.
As the news spread, locals went on the rampage, vandalizing public property and demanding arrest of the accused.
"The girl has alleged that her friend claimed to have been familiar with the place and asked her to join her on the roof of the building where they would have some fun. She has alleged that Vinod Kumar, apparently known to her friend, was consuming liquor on the roof," police said.
She also alleged that her friend and the man forced her to consume liquor as well and when the latter misbehaved with her she tried to run away but tripped and landed on the ground below, the police officer said.
The sale and consumption of liquor in Bihar was completely banned by the Nitish Kumar government in April, 2016.