Who kidnapped Arjan Erkel, 33 years old, volunteer for Médecins Sans Frontières (MSF) in the Caucasus and taken hostage 19 months ago in Daghestan, a republic neighbouring Chechnya where important military and police means are deployed?
The humanitarian organisation knows. "The head of the group that detains Arjan is a member of the Dhagestani Douma - Parliament. And his 'boss' is a member of the federal Douma in Moscow", assures Jean-Hervé Bradol, president of the French section of MSF.
Bradol says he has this information "from various sources, including from members of the forces: military, FSB (ex-KGB), police - local and federal", and has had for some months already.
Although this information has been transmitted to "Dutch, French, European, United Nations diplomats", it has not brought about any progress toward the liberation of Arjan Erkel.
"Diplomats recognise this established fact in their conversations with us but there is a public taboo. 'One cannot upset Russia', 'You will end up putting your colleague's life in danger if you keep on making noise', is what we are being told in the embassies", said Dr Bradol.
Although silent until now, the humanitarian organisation has decided to lift the taboo. The investigation on the kidnapping of Arjan Erkel is officially at a standstill.
The main investigator has been arrested and the Russian authorities in charge of this case - the Russian Ministry of Interior and the FSB - say they have no information on the kidnapers.
Meanwhile, the heads of MSF have been approached by "two or three intermediaries, all recommended by the local or federal administration, who have offered to exchange Arjan against ransom money".
The first ransom requests appeared nine months after the kidnapping, claims that came in rather late for supposedly isolated criminals. A certain sum was decided on but "all vanished at the end of December".
The level of uncertainty is total and the concern is great within MSF. "We are alarmed by recent information on the state of health and threats of execution that hang over the life" of the young man, explained the president. The kidnappers talk of "cleaning up the field before the Russian presidential elections".
The case of the kidnapping of the young Dutch volunteer, who came to help local populations who have endured nine years of war, has involved Russian or Dhagestani officials since the beginning.
At the time of his kidnapping, on August 12, 2002, a couple of days after he had met up with two American military attachés passing through the regions, Arjan Erkel was under the tight surveillance of two FSB agents who witnessed the kidnapping without reacting.
They later explained to the investigators that they could not intervene due to their lack of weapons. The number plate of the car used for the kidnapping was taken by a visual witness, but was not followed up.
In February 2003, MSF received the bill for Arjan Erkel's mobile phone, the mobile phone he had with him at the time of the kidnapping.
According to this bill more than 50 calls were made after the kidnapping. The numbers called are indicated on the bill. MSF passed on this information to the Russian authorities for their investigation.
"Some unidentified people have called different subscribers from Arjan Erkel's mobile phone. But the study of this data brought out no information deemed worthwhile.
The phone line of the hostage has since been cut off", Mr Demidov, First Vice-Minister of Interior, answered in writing.
What can a structure like MSF do? Although renowned for its humanitarian action and awarded the Nobel Peace Prize in 1999, it is entirely helpless in the face of such manoeuvres. Bradol is appalled: "Hostage-taking is something we know in MSF.
But in this present case we are not facing an isolated group of kidnapers hiding in the forest.
This is not FARC (Revolutionary Armed Forces of Colombia). We affirm that local and federal members of the Russian administration are involved in the negotiations and are taking advantage of it.
"Since when is human trafficking seen as a regular recognised political practice? Is this the norm of the relationship between Russia and the European Union? How much longer can we ignore that human trafficking, the corpses, that rape and torture touch thousands of people in Chechnya?"