One of the three persons detained in connection with the attack on Indian Institute of Sciences in Bangalore had visited the prestigious institute on the morning of December 28, the day of the incident, informed sources said.

The person is understood to have been enquiring about the topography of the auditorium where a seminar was being held, they said.

• Terror attack at IISc, Bangalore; 1 killed, 4 injured

The attack had taken place in the evening when delegates from the seminar were heading for dinner.

The detained person was identified by the wife of an officer of IISc who had told the investigators that the person had been enquiring about the auditorium in the morning, said the sources.

The sources said it was unlikely that a person, who wants to carryout an attack in the evening, would conduct a recee in the morning, but still nothing was being left to chance and the antecedents of the detained persons were being checked.

Security officials probing the Bangalore attack had found the imprint of Pakistan-based Lashker-e-Tayiba in the attack that left a retired Delhi Indian Institute of Technology professor M C Puri dead and four others injured.