Investigators probing the bomb threat call have found that the anonymous call was made from Tiruchi using a cell phone.

Studying the call details of the mobile number, the police found that the call was made from Tiruchi and immediately got in touch with that number. The tower locations of the anonymous caller showed different places in Tiruchi on Wednesday morning.

Later, two short text messages received from the same cell phone number to GRP personnel – one threatening that a bomb had been planted in the train and another conveying “sorry.”

Police sources said a pre-paid SIM card was used for making the threat call and the address of the SIM card-holder had been traced to Thiruverkadu in Chennai.

The sources said the Cantonment police had received a complaint from a city resident in May that an anonymous caller had abused him over the phone.

He had mentioned in the complaint the cell phone number from which he got the call.

It was the same number from which the bomb threat was made on Wednesday.