The accused, identified as Umay Arun Sakpale (21) was arrested yesterday for raping the victim, daughter of a police constable posted at Nalasopara, while his mother Aparna (49) was held allegedly on abetment charge, police said March 27.
The accused had befriended the victim on a social networking site in August 2012.
"Initially they used to frequently chat online. However, soon they started meeting and went for shopping,outings and watched movies," Mukund Mahajan inspector of the Nalla Sopara police station of Thane district said.
One day, the accused took the girl to his house and offered a cold drink laced with sedatives, following which she fell unconscious.
"From there, he took the girl to a lodge and allegedly raped her there. He also took obscene pictures of her. Then he took the victim back to his own house and introduced her to his mother.
The youth had already told the girl that his mother was in favour of their marriage," Mahajan said.
Later, the youth started blackmailing her threatening that he would upload her obscene picture on the networking site and raped her on several occasions, police said.
The victim recently narrated the entire episode to her uncle, who took her father into confidence and approached Pant Nagar police station to lodge a complaint.
An offence was registered against the youth and his mother and the duo was arrested last evening.
Further investigation into the case is on.