HOURS after a Russian airliner—Metrojet flight 9268—crashed in the Sinai Peninsula last October, killing 224 people, the Egyptian affiliate of Islamic State (IS) claimed responsibility. Less than a week later, Britain said it suspected that a bomb was the cause. American officials concurred, fingering IS. Two weeks after that, Russia concluded that a “terror act” brought down the plane. Case closed, it seemed.

But Egypt dismissed each suggestion as premature. In December its investigators issued a preliminary report stating that there was no evidence of terrorist activity or a security failure. They still have not produced a final report (publicly, at least). Only in February did Egypt’s president, Abdel-Fattah al-Sisi, obliquely admit that the crash was an act of terrorism.

Now Egypt is investigating another crash, that of EgyptAir flight 804, which went down in the Mediterranean Sea on May 19th, killing 66 people. Ayman al-Moqadem, the head of Egypt’s investigation team, who also led the Metrojet inquiry, says a preliminary report will be ready in a month. Few think it will shed much light on the crash, especially if the cause embarrasses Egypt.

“Investigations take time, there is no need to rush to conclusions,” says Mr Sisi. But Egypt is developing a knack for interminable probes that lead nowhere, or that produce self-serving results. Some are reminded of EgyptAir flight 990, which crashed off the coast of America in 1999. American officials said the Egyptian pilot brought down the plane, citing ample evidence. Egypt spent millions of dollars trying to prove otherwise.

More recent examples abound. Take Egypt’s investigation into the killing of eight Mexican tourists and four Egyptian guides in the Western desert last September. There is little argument over what happened: the military hit the group with an airstrike. But Egypt’s “transparent” inquiry was undercut by a ban on reporters covering the incident, or the probe. No findings have been released, though Egyptian officials blamed a travel agency for bringing the tourists to a restricted area. On May 12th the Mexican foreign ministry expressed “surprise and dissatisfaction” at the less-than-thorough investigation.

Italy has reacted even more forcefully to Egypt’s investigation of the murder of Giulio Regeni, an Italian studying Egyptian trade unions, a sensitive subject, in Cairo. Regeni disappeared on January 25th; his body was found two weeks later bearing signs of torture, a hallmark of the security services. But investigators proffered other explanations for his death and declined to question the authorities. In March the Egyptian police claimed to have shot dead those responsible: four men who “specialised in impersonating policemen, kidnapping foreigners and stealing their money”.

Few people outside of Egypt are buying it. Italy recalled its ambassador in April due to a lack of co-operation from the Egyptian authorities, who have not shared pertinent video footage or phone records, say Italian officials. Several questions remain unanswered, such as: why did the kidnappers keep Regeni’s belongings for weeks after killing him? Why would thieves torture him for days? And why were they not arrested instead of killed? No one expects the answers to come from Cairo.

Egyptian investigators are already sparring with others (and between themselves) over details of the latest EgyptAir crash. They have dismissed speculation that the plane lurched before falling, or that there was an explosion on board. The pro-government media portrays such conjecture as a foreign conspiracy aimed at weakening Mr Sisi, who claims to be Egypt’s protector. The crash is likely to do further damage to the tourism industry, a mainstay of the economy and important source of foreign currency.

Mr Sisi himself has already complained about “an attempt to obstruct our investigations”. He has ordered officials to keep the public informed of any discoveries, echoing statements he has made in the past. “We won’t cover anything up,” he said shortly after the Metrojet crash, while his government is failing to uncover the truth.