India, Nov. 17 -- Investigators tracing the final days of Umar un-Nabi - the man behind the wheel of the Hyundai i20 that exploded near Delhi's Red Fort last Monday - detained the owner of a medical shop in Dhauj who police described as a "friend" of Nabi and one of the last people to speak with him in Faridabad before the suspected suicide bomber moved base to Nuh under an alias.

The shop owner, who investigators privy with the case said had known the 35-year-old doctor for nearly a year, became a key figure on Sunday as teams in Faridabad tried to reconstruct how Nabi slipped out of the city, rented a room under the name "Mohammad Afsar," and moved to Nuh as investigators arrested his associates and unravelled their module.

Meanwhile,...