New Delhi, May 11: A 44-year-old Russian national died after falling unconscious at the FRRO office while his deportation formalities were going on, police said today. Sergey Erin died on Wednesday afternoon at AIIMS, they said.

Erin was detained in the early hours of Wednesday after the police were informed that a man was acting violently and pelting stones at passersby near Inderlok in north Delhi. Some locals had tried to control him but Erin was banging his head on the road and hitting himself. He also resisted accompanying the police personnel when he was asked to do so, they said.

At 3 am, he was taken to the Sarai Rohilla police station and then to the Bara Hindu Rao hospital for a medical exam where the doctors said he had minor abrasions, police added. In the morning, the police personnel took him to the FRRO office in RK Puram for completing his deportation formalities.

During lunch time, he fell unconscious and was rushed to the All India Institute of Medical Sciences (AIIMS) where efforts were made to resuscitate him. The doctors later declared him dead, they added.

Police said he was suspected to have suffered a cardiac arrest but a post-mortem report would confirm the exact reason of his death.

The police launched an investigation into Erin's death and it was probing whether he was attacked by locals on the night of his violent outburst.