Call for new 'assassination' inquiry
Parliamentarians are demanding yet another inquiry into Portugal's most intriguing and enduring political mystery, the death of former Prime Minister Francisco de Sá Carneiro and his defence minister, Adelino Amaro da Costa.
Thirty years ago, on 4 December 1980, a light plane carrying the two politicians crashed soon after take-off from Lisbon Airport. They were on their way to a presidential election rally in Oporto.
Conspiracy theories about the cause of the crash persist despite no fewer than eight previous commissions of inquiry. Accidental death was the original official explanation. The crash was blamed on technical failure and pilot error, but many Portuguese remain convinced the plane was deliberately blown up.
Sá Carneiro was a founder of the Popular Democratic Party, which later became the Social Democratic Party (PSD). He had been prime minister for only 11 months when he boarded the aircraft, a Cessna 421, on that fateful night.
Eye-witnesses said they saw pieces falling from the plane moments after it took off. The strongest conspiracy theory suggests that Sá Carneiro and da Costa were the victims of an assassination plot connected to an arms-for-hostages deal and a rigged US presidential election.
The crash occurred the year after the revolution in Iran that brought Ayatollah Khomeini to power. Fifty-two Americans were taken hostage when youthful Islamists stormed the US Embassy in Tehran in November 1979. The hostages were held for 444 days from 4 November 1979 to 20 January 1981. Following the spectacular failure of a US military rescue operation with eight US servicemen and one Iranian civilian’s dead, President Jimmy Carter resorted to diplomatic efforts.
Conspiracy theorists believe da Costa had information that senior Portuguese army officers were secretly passing arms to Iran as part of a plot by US Republicans to damage Carter's re-election campaign during this time.
Ronald Reagan and his vice-presidential candidate, George Bush Sr, were said to have struck a deal with the Iranian leadership to have the release of the hostages delayed until after the election in order to give them an electoral advantage.
It is thought that da Costa was targeted because he had uncovered evidence of a secret Portuguese army slush fund to be used for arms deals. He was allegedly killed to conceal evidence of the illegal arms movement through Portugal, which he was determined to stop.
Experts on IRA and ETA bombs have been among those suggesting a high-level campaign to conceal the truth.
After 30 years and eight commissions of inquiry, Portuguese parliamentarians of all parties are now being urged to demand a fresh inquiry in the hope that the truth will finally be revealed.