Georgi Iliev, investigator from the National Investigative Services, failed to confirm his Sunday statement that the probe has decisively proven the alleged perpetrator of the terrorist act in Bulgaria's Burgas was a suicide bomber.

Speaking for the largest, private TV channel bTV on Monday, Iliev stated that he had never said categorically that the attacker has been a suicide bomber. He explained that there were two main leads: the suicide bomber one being first, while the second is that he had accomplices.

"There is no proven evidence that this individual had sacrificed his life to perpetrate the terror act. He is just one of those who did it. We cannot say either what his or their exact goal was," said Iliev.

Speaking Sunday for the Bulgarian National Radio, BNR, Iliev declared the probe had decisively proven that the perpetrator was a suicide bomber, contradicting a number of recent reports and leads that the man has been deluded, used as a mule, and has acted under the influence of illegal drugs.

"This has been a suicide bomber, a man who knowingly sacrificed his own live in order to cause the death of many others. He is a foreign citizen who has chosen Bulgaria for this act," the investigator adamantly stated one day earlier.

When asked why weeks after the bombing the public still does not know the identity of the man and who is behind the attack, Iliev noted that there are many examples across the globe showing it could take years to solve such cases over the hurdles before the investigation.

The July 18 terrorist attack in Bulgaria's Burgas, also known as the Burgas Bus Bombing, killed 5 Israeli tourists and a Bulgarian bus driver at the Sarafovo Airport. The initial lead, purported by Interior Minister, Tsvetan Tsvetanov, was that it has been executed by a suicide bomber, who arrived from abroad.

According to observers and terror experts, this lead is looking less and less reliable and the most sustainable hypothesis is that the perpetrator has been used as a mule.

Israeli media largely back the above, writing that the young man with light complexion and blue eyes had been blown remotely, while standing between two coaches with Israeli tourists. He had been unaware that he was going to die and had the task to put the explosive on one of the buses. The bomb was placed in his backpack.

In the Monday interview, Iliev confirmed that some of the tourists, who witnessed the attack, will be interrogated once again.

He reiterated that the Bulgarian authorities have sent to Israel their questions to some witnesses of the blast, who could not offer viable testimony right after the incident because they have been sedated and/or on other medications.

After being questioned by the authorities in Israel, the testimony of the survivors will be sent back to Bulgaria to be attached to the case.

The new questioning further aims to confirm witness accounts that the terrorist had an altercation with one of the tourists right before the explosion. The wife of one of the victims has said that her husband entered into an argument with the man because he moved some bags in the luggage compartment of the bus in order to place inside his own one.