Sources close to the investigation into the murder of journalist Daphne Caruana Galizia have hinted at the possible involvement of foreign individuals in the macabre case.

Caruana Galizia, who was a columnist for The Malta Independent, was killed on Monday when the rental car she was driving was blown up just a few metres from her house. She had left to run some errands at around 3pm. The material used in the bomb has been identified as Semtex – a military grade explosive that is not available in Malta.

The sources, who are close to the Armed Forces of Malta, said the material was probably smuggled to Malta illegally. This would be the first time that Semtex has been used in bombings in Malta.

Pyrotechnic material was used in most other cases, where the devices were manufactured locally. But the material used this time was a type of military plastic explosive, which is many times more powerful.

The sources said the bomb could have been brought to Malta ready assembled or it could have been smuggled in separate components and put together in Malta. However, it is believed that there are no people who are skilled in the use of Semtex.

It is also understood that investigators are ruling out the possibility that the bomb was attached to a time, with sources pointing out that the case bears similarities to the car bombing in St Paul’s Bay last year. In that case it was believed that the car was being followed by a person holding the mobile triggering device.

Several forensic experts from Malta, the Netherlands and the US (FBI) were yesterday still combing the scene of the crime, which is still cordoned off. Members from the UK’s Scotland Yard yesterday joined in the investigation.

The rental Peugeot was yesterday evening transported from Bidnija to the police compound in Pembroke, where investigations are continuing.

The car arrived in Pembroke at around 6.50pm, escorted by at least four police cars and another two unmarked cars, thought to be CID.

The journalist’s body was also removed from the site yesterday and an autopsy will be carried out in the coming days.

Erlier in the day white clad figures could be seen examining several spots and picking up pieces of evidence. Our sources said the forensic experts would have analysed what kind of explosive was used by taking samples from the car, the road and the body.