Though there were reports about the use of a black vehicle in the attack, Delhi Police were still sticking to the use of the red two-wheeler in the incident which took place on Aurganzeb Road near Prime Minister's residence last Monday.
Israeli diplomat Tal Yehoshua-Koren and her Indian driver were among the four persons injured in the incident, which Tel Aviv alleged was the handiwork of Iran. Investigators maintain that they have nothing to point fingers at Iran as of now.
Police and Israeli officials have reconstructed the incident more than two times in search of clues but the probe had not moved. Delhi Police Commissioner B K Gupta had said the investigations were gathering pace.
The two attacks in Thailand and Georgia had prompted the Indian investigators to reach out to the countries for input.
Sources had earlier said while C-4 explosive material had been used in the failed Bangkok plan, there was so far no traces of such explosive having been used in the February 13 case.
According to the sources, none of the three Iranians arrested in Bangkok and Kuala Lumpur had ever visited India as Immigration records showed no entry of their passports, as provided by the two authorities.
Police had seized several red colour motorcycles and detained suspects but all were let off later as they could not be linked to the attack.
Scanning of telephone calls made to Iran, Pakistan and middle-eastern countries around the time of the attack also yielded nothing, the sources said.