The men suspected to be behind Tuesday's serial blasts that killed at least 61 people and injured 216 had made their most significant purchases from seven bicycle shops in the walled city area without attempting to bargain and spoke Bengali, police sources said.
Ten bicycles were used for the serial bombings - nine were brand new and the last one, which has left security officials in a tizzy, was a used one.
"All cycles were purchased a day before and on the blast day. They went to each shop twice in two days. On the first day they went to check the various cycle models and next day the suspects went to the same shops to purchase the cycles," a police official told IANS on condition of anonymity.
The men were dressed in blue jeans and white shirts, the shopkeepers had told the police.
"The men did not see any of the owners and only dealt with their employees. They paid whatever money was asked for the bicycles without bargaining and hesitation and went away immediately.
"The employees have told us that they did not look like Rajasthanis and spoke in broken Hindi. In fact they were speaking Bengali, which has again given rise to speculation that the militants were from a Bangladeshi outfit," the official added.
According to him, the bicycle used for the blast at the Chandpole Hanuman temple was bought from Santosh Trading Company. The cycle used for the bombing near Sanganeri Gate was bought from shop number 84 Hemraj Cycle Store. For blasts near National Handloom in Chhoti Chapuad, two cycles were bought from Nanad Cycles.
One cycle was bought from Cycle Haat to carry out a bombing near Tripolia Gate. For the Kotwali blast, the cycle had been bought from Krishna Cycle Store.
The cycle that failed to explode at Sawai Mansingh Hospital was bought from Shankar Cycles in Kishanpole area. The cycle bearing the brand name "Naked Aggression" was manufactured by Surya Cycles.
The terrorists had used one old bicycle to trigger the explosion at Johori Bazaar. Two bicycles were also purchased from these shops for blasts at Manak Chowk and Badi Chapuad - both a hand-shaking distance from the famous tourist landmark Hawa Mahal.
The modus operandi of the Jaipur blasts is similar to the serial bomb blasts in Uttar Pradesh courts in November 2007, the Mecca Masjid blast in Hyederabad in May 2007 and the Malegaon blast in 2006 where bombs of medium intensity were planted on bicycles.
At that time investigating agencies had strongly suspected Bangladeshi militant outfit Harkat-ul-Jehad-al-Islami (HuJI) of being behind the attacks. Working on some leads, police teams are raiding Bangladeshi localities at Galta Gate, Baghrana, Ramganj, Subhash Chowk and Bhatta Basti in Jaipur.
Sources said investigation teams from the Delhi Police Special Cell, Maharashtra Anti Terrorism Squad and Uttar Pradesh Special Task Force - all expert wings in combating terrorism - are already probing on similar lines.
Arvind Gulati, owner of the Cycle Haat, confirmed to IANS that his employee Arif had sold a bicycle to one of the suspects.
"Police have taken Arif into custody and are still interrogating him. Arif is assisting them in making a sketch," Gulati said.
So far, after questioning all the employees of bicycle shops, police have released four sketches of the suspects, all men in their early 20s.