Police sources said they were also examining telephone calls made from New Delhi area in the past few days to ascertain whether it has any connection with the attack.
A senior police official said they were specifically looking into a few calls made to Iran, Lebanon and Pakistan from Khan Market area where Tal Yehoshua-Koren, the Israeli diplomat, had lunch with her husband, before she was attacked.
However, the sources said, they were yet to link these calls with the attack.
Overnight raids and intensive search for a motorcyclist who carried out a car bomb attack on an Israeli diplomat have yielded very little so far.
Delhi Police Commissioner B.K. Gupta said investigations have gathered pace but was still in the initial stages.
Police questioned several people during the raids in the past four days but is yet to get any breakthrough in the incident.
Israel has accused Iran of orchestrating the attack on their mission staff here and in Bangkok and Georgia.
“Investigations are in the initial stage. It is gathering pace,” Mr. Gupta told reporters here on the sidelines of a function to commemorate the 65th Raising Day of Delhi Police.
He said the sleuths of special cell are investigating the Monday attack. They were awaiting CFSL report which would throw more light into the composition of the bomb and explosives used, he said.
Police has also sought the help of Foreigner Regional Registration Offices (FRRO) in collecting details of people from Iran, Jordan and Lebanon residing in Delhi.
Sources said they were also looking into the possibility of a foreign terrorist organisation hiring a local terror module to carry out the attack.
Police is also collecting data about similar attacks that have taken place in the last ten years across the world.
Sources said Israeli officials in their meetings with Delhi Police have pointed fingers at Iran but have not shared any specific input.