"Chintoo surrendered today and the court has remanded him in judicial custody for two weeks," a senior police official said.
Chintoo, nephew of Mohan, has been on run since the couple, both TDP leaders, were allegedly shot at and stabbed to death by at least six persons in the office of Chittoor Municipal Corporation on November 17.
With Chintoo turning in himself today, the number of people arrested by the police so far has reached four.
A case was already registered under charges of murder and other relevant sections of the IPC and under Arms Act against all the accused including Chintoo.
Police had earlier said that the attack was carried out following a family dispute.