In her petition to District Collector L Subramanian, 57th ward councillor G Khader ammal said her husband had been receiving anonymous threatening calls. The caller had rung up '108' ambulance service four times, informing them they had been hacked by some people and were in serious condition. Each time the ambulance service had responded and found it false.
She said a handwritten poster was found near her office on June 5, stating that they would be killed if she did not quit her post and vacate her house.
Under the circumstances, they felt "the safest place for them was in prison".
"Our efforts to trace the culprits have not been successful" they said.
Supporters of the councillor also held aloft placards demanding that the culprits be arrested.