A doctor allegedly committed suicide on Saturday morning in south Delhi's Neb Sarai area, police said.
A suicide note recovered from the victim's house stated that AAP MLA Prakash Jarwal was responsible for his death, they said.
The victim has been identified as Rajendra Singh (52), a resident of Durga Vihar, police said.
According to the police, Singh hanged himself with the help of a rope at his house.
A tenant noticed the body around 5.30 am and informed his family members, a senior police officer said.
The body was sent to AIIMS for postmortem, he said.
Meanwhile, the victim's son alleged that his father used to run a clinic in the locality and was also in the business of water supply with the Delhi Jal Board since 2007, police said.
A case of extortion, abetment of suicide and threat has been registered against the Deoli MLA, one Kapil Nagar and others at Neb Sarai Police Station based on a complaint by the victim's son, they added.