The body of maid Rakhi, with several injury marks on her legs, chest and arms, was recovered from Singh's residence at South Avenue here last evening after the MP himself informed the police.
Jagriti was taken into custody this morning and questioned for 12 hours, investigators said.
An FIR was registered against her at Chankyapuri police station under sections 302 (murder), 307 (attempt to murder), 344 (wrongful confinement) of Indian Penal code and Juvenile Justice Act. Police are mulling to add sections under Bonded Labour Act for hiring a juvenile.
They said the injury marks were visible on arms, legs and chest. Police are also questioning Dhananjay to ascertain his role in the case.
Another minor help, who has been working at the household for the last one year, told police that he was also beaten up badly by Jagriti.
"The maid must have been beaten up mercilessly as her body bore several old and fresh injury marks," said a senior police official.
Jagriti has called Dhananjay and informed him about the maid's death, police said.
Rakhi had been working at the MP's residence for the last 10 months. According to police sources, Jagriti had been allegedly torturing her maid during this period.
"Although she was torturing her for past many months, but the frequency of beating had gone up since November 1," said a senior police officer.
