The exact cause of death of drug trafficker Mario Camilleri, known as l-Imnieħru, is mired in a medico-legal argument more than six weeks after he was found partly buried with his son in a Birżebbuġa field.

Follow-up tests on the second post mortem ruled out that the two holes in Mr Camilleri’s skull were the result of any surgical intervention, Police Commissioner Peter Paul Zammit told The Sunday Times of Malta.

Although the second post mortem was carried out on July 30, the results have not been available until now.

“The holes are fresh and they’re not machine-made. The puzzle remains because the bullets haven’t been found,” Mr Zammit said when contacted.

However, he stressed that while the bullets were never retrieved this was not much of an anomaly as they could have exited through the mouth cavity “or as may yet be established through further examinations if required”.

The fact Mr Camilleri’s body was badly decomposed further encumbers investigations.

Questions have lingered on the exact cause of death ever since he was found in a shallow grave in Qajjenza on July 17. The death of l-Imnieħru’s 21-year-old son, also named Mario, was more clear-cut: he was shot and stabbed 34 times.

While forensic experts are insisting Mr Camilleri Sr died of an “acute coronary thrombosis” that led to a heart attack, the police say they have statements from two men charged with the murders of the 51-year-old and his son – l-Imnieħru’s brother-in-law Jason Galea, and George Galea – that they carried out the kills. However, the men have pleaded not guilty to murder.

As far as police are concerned, the holes in his skull led to his death

The police theory is also backed by the results of the second post mortem that revealed the presence of two holes in the skull. It also concluded that the heart stopped, but according to the Police Commissioner the “heart issue is secondary”.

“As far as the police are concerned, the holes in his skull led to his death – this was established through hard evidence corroborated with factual evidence. That wins over any other conjecture,” the Police Commissioner said.

This line of investigation is further supported by comments Mr Camilleri’s wife Mona gave to Times of Malta last month that her husband had “never suffered from heart problems or injuries to the head”; nor had he had any surgery that entailed holes in the skull.

Asked what was stalling the investigation, Mr Zammit pointed to the results of the first post mortem – which concluded Mr Camilleri died of a heart attack – and the fact that the bullets were never found.

In the coming days, he said, police would be asking the court to bring together the two teams which carried out the two post mortems.