Trinitrotoluene, an explosive material, was used in the February 13 bombing of an Israeli diplomat's car in the high-security area of the capital, the Central Forensic Sciences Laboratory said in its report.
CFSL experts handed over the report recently to the Delhi Police giving its opinion about the explosive material used in the bombing of the diplomatic vehicle of Israeli diplomat Tal Yehoshua, who was seriously injured in the incident and was later flown back to Israel.
The CFSL had deputed its senior scientists for establishing the explosive material used in the terror incident, a first of its kind in which an envoy was targeted by assailants from a different country.
"It is established from samples picked from the scene of crime that TNT was used as explosive material," the 31-page CFSL report sent to the Delhi Police said.
TNT, which was first used in 1902 as an explosive material when Germans filled it in artillery shells, is termed as an insensitive explosive which enables it to be poured while in liquid form into shell cases. TNT is insensitive to shock as well as friction, which allows it to be transported and used without much risk for accidental detonation. It is also water-resistant, which allows it to be used in wet environments.
The report also talks about pieces having magnetic nature which could have been used by the terrorist identified as Houshang Afshar Irani for sticking the bomb on the envoy's car which also left four other people with minor injuries.
According to the investigators who have been closely coordinating with intelligence agencies of other countries, the terror attack was allegedly carried out by Tevhid-Selam-Quds, an organisation which is being handled from Iran. Its operatives are trained and equipped with weapons, ammunition and explosives especially in handling of TNT and C4.
The members of this group have a history of carrying out terrorist attacks on Israel like those in Turkey which includes the murder of Israeli security officer Ehud Sadan.
The investigators had recently arrested journalist Syed Mohammed Ahmed Kazmi, who was working part-time for Iranian news agency and other Persian newspapers, for allegedly being a part of conspiracy of bombing the Israeli diplomat's car.
The National Bomb Data Centre, which comes under the elite NSG, was kept away from collection of samples at the blast site by the Delhi Police despite being the central nodal agency for monitoring, recording and analysing all bombing incidents in the country and act as the vital repository of all domain knowledge in this regard.
The NBDC charter mandates the NSG to send its post blast study teams to all places where a blast has occurred in the country and collect samples from the spot.
Kin of Kazmi claimed he was innocent but the Delhi Police had alleged in the court that the February 13 bombing in the heart of the capital was a case of "international terrorism" and Kazmi had allegedly helped the bomber conduct reconnaissance of the Israeli embassy.