Tariq Ahmad Dar, alleged to be a key member of the Pakistan-based Lashkar-e-Tayyaba group, was arrested on Thursday in the Kashmiri city of Srinagar and brought to the capital on Friday for interrogation, Delhi Police commissioner KK Paul said on Sunday.
He said it was clear from the investigations and Dar's interrogation that Lashkar-e-Tayyaba was behind the near-simultaneous bombings in three crowded markets that killed 60 people and wounded more than 200 before two major festivals, Diwali and Eid al-Fitr, when thousands of people were doing last-minute shopping.
"They wanted to create maximum impact," Paul said.
He said police cannot reveal any more evidence, but based on "what he [Dar] has told us, and the details we have, there is sufficient evidence to prove the conspiracy," he said.
Dar has not been formally charged, but police have obtained a court's permission to detain him for 14 days for further investigation to help catch at least four other suspects, including those who planted the bombs, Paul said.
Dar was not in New Delhi on the day of the bombings, but he is "an important financier, conspirator and coordinator of Lashkar," said Paul, adding that Dar works as a sales representative for a pharmaceutical company in Srinagar, the summer capital of Indian-administered Jammu-Kashmir state.
The Sarojini Nagar market was
one of three bombed sites
"But he has intimate contacts with Lashkar, and he works as their facilitator," Paul said.
Lashkar-e-Tayyaba is one of the most prominent of Muslim separatist groups fighting Indian security forces in Jammu-Kashmir, the only Muslim-majority state in predominantly Hindu India.
More than 60,000 people have been killed since 1989 in the fighting in Kashmir, which is divided between India and Pakistan. Both countries claim the territory in its entirety, and the separatist groups want either independence for the state or its merger with Pakistan.
Paul said Dar's bank account received a deposit of 500,000 rupees ($10,900) from abroad a few days after the bombings.
He is alleged to have been in New Delhi between 4 and 6 October to scout the locations where the bombs were to be planted.
At least seven other people are thought to have been involved in the conspiracy, four of whom have been identified by name, Paul said.
He said no more information can be given because investigations are in progress.