Last year I asked Mohamed Nur, the mayor of Somalia's capital Mogadishu, for an assessment of the threat that al-Shabaab still posed beyond the country's borders.

The militants seemed to be on the back foot, demonstrated by the fact that we were sitting in the Somali capital sharing sandwiches, as we waited for William Hague to fly in. For the first time in 20 years, it was considered safe enough for a British Foreign Secretary to visit.

“But don’t be fooled, the terrorists are still here,” said Nur, who is nicknamed 'Tarzan'. “One day our problem will become your problem”.

He should know, given his unique insight into the relationship between Britain and Somalia. As well as running the city once considered to be the world’s most dangerous, he used to live in London working as a Labour Party activist and running an internet café.

He saw it as inevitable that a militant group which was then thought to have 50 British members – perhaps more now – would always pose a threat to the UK.

Kenyan soldiers and forensic officers search the Westgate shopping centre in Nairobi for clues Credit: Reuters

The Westgate Mall stand-off was a ‘foreign attack’ in a neighbouring country. But there’s no surprise that British investigators have travelled to Nairobi to help Kenyan police investigate. One fear now will be that the al-Shabaab militants – pushed back at home – might be plotting so-called ‘asymmetric attacks’ even further afield.

But local newspapers are suggesting that the visiting foreign detectives – which include American, Israeli and German teams - might not be getting the full access that they want. Some are threatening to pull out, one report says, after they were told that they can’t have DNA samples from the five militants who were killed by the Kenyan Defence Force.

Withholding important details from the public, citing national security grounds, is one thing. But keeping details from international investigators trying to build a profile of the terrorists to share around the world would be another.

Kenyan soldiers enter the main gate of the Westgate shopping centre in Nairobi Credit: Reuters/Goran Tomasevic

These new reports will only compound the sense of secrecy surrounding the Westgate investigation, and add to the list of unanswered questions: If DNA cannot be gathered, have the bodies of the killers been retrieved and identified?

Have the police worked out whether any of the terrorists escaped from the Westgate Mall during the four-day stand-off?

And what more is known about whether foreigners were among those who stormed the shopping centre 10 days ago?

We still don’t know, we still don’t know, we still don’t know.