Arumugham allegedly attacked the doctor suddenly and also strangled her neck using a wire.
Police Monday cracked the case relating to the murder of his mother-in-law and his mother in 2015 and 2017 with the arrest of a 60-year-old man, hailing from Chennai, for allegedly attacking and robbing a doctor of her jewels in her clinic.
On Sunday, Arumugham entered the Siddha practitioner Tamilselvi's clinic near and sought treatment for his ailment, senior superintendent of police Apoorva Gupta told newsmen.
During diagnosis, Arumugham allegedly attacked the doctor suddenly and also strangled her neck using a wire, the police official said.
The doctor fainted and the accused allegedly decamped with seven sovereigns of jewels she was wearing, the official said.
When she regained consciousness she found the jewels missing and the shutters of the clinic down, he said.
Arumugham was said to be a regular visitor to the clinic, he said.
When Tamilselvi cried for help, people in the neighbourhood rushed to the rescue and shifted her to JIPMER hospital, he said.
Based on her description of the accused, a trap was laid and Arumugham was arrested near, the police official said.
During interrogation, the accused confessed to have murdered the two women; and his associate Sathish, 34, who helped him in dispensing with the stolen jewels was subsequently held near, he said.
Arumugham and Sathish were produced before a local court and remanded to 15 days judicial custody.