Rekha allegedly committed suicide by hanging herself from the ceiling fan at her in-law's house on Saturday afternoon. She was a dentist and married to Sudhanshu (30), who is an advocate, around 11 months ago.
The former legislator and three members of his family were arrested yesterday.
Rekha's family had been alleging that their daughter was killed for dowry.
Rekha's family members, who were protesting outside Babu Jagjivan Ram hospital, tried to block Outer Ring Road. They left the spot only after police's assurance.
The woman's parents also expressed their concern to the police that being politically connected, Rekha's in-laws could "manage" the post mortem examination report.
A senior police officer said post mortem would be conducted tomorrow morning at Safdarjung Hospital. "Besides that a medical board would be constituted," the official said.