The sources told IANS that the couple has been lodged in separate rooms at the Chanakyapuri police station and are allowed home cooked food - a practice contrary to norms.
The sources said while Dhananjay Singh, who represents Jaunpur Lok Sabha constituency in Uttar Pradesh, has been given the rest room of a sub-inspector, his wife is kept in the rest room of an assistant commissioner of police.
The usual practice is to keep the arrested people in a lock-up when they are in policy custody.
"Home food is never allowed for the accused," said a source. "They are getting lunch from home but breakfast and dinner is served from the police canteen."
While Dhananjay Singh has been arrested and booked for destroying evidence and violating provisions of the Juvenile Justice Act, his wife has been charged with murder, attempt to murder and violating Juvenile Justice Act.
Police say the MP's wife beat and tortured her maid Rakhi, 35, and Rampal, 17, for days. The MP and his wife were arrested Tuesday.
Jagriti is the second wife of Dhananjay Singh, whose first wife committed suicide in 2007. Jagriti is a senior resident doctor at Ram Manohar Lohia Hospital in the heart of the city.
"During interrogation, she (Jagriti) broke down once. Now she is her normal self and talks with the police station staff. But the MP rarely speaks. When he does, it is mostly to senior officers," the source added.
Neither has shown any remorse, the sources said.
According to police, Jagriti beat up Rakhi and Rampal Sunday night over a petty issue with an iron rod and sticks.
She also used an iron press and horns of a dead animal while beating them. Both of them received grievous injuries.
Delhi Police received a call from the MP's 175, South Avenue house Monday night, informing them about Rakhi's death. The information was given by the MP himself but he tried to mislead the investigators, police said.