By Mark Doyle
BBC News, Abuja, Nigeria
Alhaji Abdulmutallab warned agencies about his son
One of Nigeria's two main intelligence agencies has blamed the other for failing to share key information two months ago about Umar Farouk Abdulmutallab, the young man who allegedly went on to try to blow up a plane over the United States with nearly 300 people on board.
If the charge is confirmed, it could highlight disarray within the Nigerian intelligence community which parallels the mistakes President Barack Obama said had been made by US officials.
The reported failure by one part of the Nigerian government to share information with other parts of the administration could also, of course, have had potentially catastrophic consequences - although, in the event, Mr Abdulmutallab allegedly failed to completely detonate explosives on the plane.
This story begins in the spacious grounds of the Abuja headquarters of the Department of State Security, DSS (formerly, and still better-known in Nigeria as the "SSS" - the State Security Services).
The DSS building is protected by high walls.
Its gates are guarded by plain clothes agents wielding new and lethal-looking machine guns. The agents told me the guns were of Israeli manufacture.
Inside the walls, a large white multi-story building sits amid attractive, manicured grounds with flower gardens and hedges.
Inside the offices two senior DSS officials told the BBC that Nigeria's other main security outfit, the Nigerian Intelligence Agency (NIA) had not shared key information given to it by the father of the suspect - information which could potentially have stopped Mr Abdulmutallab boarding the plane.
Umar Farouk Abdulmutallab has been charged over the incident
The father, respected Nigerian banker Alhaji Umaru Abdulmutallab said in a written statement on 29 December that when he became concerned about the behaviour of his son, who was living abroad, he signalled this concern "to the Nigerian security agencies about two months ago and to some foreign security agencies about a month-and-a-half ago, then sought their assistance to find and return him home."
The two senior DSS officials - who gave me their names and allowed me to take notes throughout a 20-minute interview - said the agency that Mr Abdulmutallab Sr had briefed had been the NIA.
The DSS officials went on to claim that although their agency was responsible for maintaining airport "watch-lists" of people under suspicion, the NIA had not shared the father's information with them.
The DSS officials explained that their agency dealt with Nigeria's internal security while the NIA was responsible for external threats.
The NIA has yet to comment on the allegation.
I drove to the NIA's Abuja headquarters - which are also in spacious grounds surrounded by security fencing - in search of their comments.
At a gated checkpoint, there were more plainclothes security men - this time with older-looking, but, of course, still lethal machine guns. I guessed they were AK47 Kalashnikovs.
The security men here were polite but did not allow me to proceed to the main office - another large white building that I could see in the distance, this time festooned with communications aerials and satellite dishes.
The plainclothes agents appeared, in fact, to be soldiers - because they stood to attention and barked salutes when senior officials drove through the gates.
These agents said I could not proceed to the offices because the NIA public relations officer was not present - or "on seat", as they say in Nigeria. I left my card and was promised that the spokesman would call me by phone immediately on his return. He has not called.
When I asked Nigerian Foreign Minister Ojo Maduekwe about the DSS officials' allegations he told me he would reserve judgement on the truth of the matter pending government enquiries being led by the Vice-President Goodluck Jonathan.
President Umaru Yar'Adua is in hospital in Saudi Arabia with a serious heart complaint.
The apparent dispute between the two Nigerian intelligence agencies is one more riddle in a dangerous affair which has rocked the United States and Nigeria alike.
Nigeria says it will beef up security at its airports with more and better body scanners in response to the Christmas Day incident.
It would be unfair to single out Nigeria as a uniquely insecure travel hub.
There will be stricter procedures in place now at Nigeria's airports.
Its airports are far better organised these days than, say, 10 years ago.
But sceptical Nigerian travellers say there is still a "big man" syndrome at play here where the rich or well-connected can sometimes be waved through by junior staff unwilling to challenge them.
Perhaps all that will now change.
But on the very day that the Nigerian Civil Aviation Authority was announcing its new, stricter procedures, one traveller leaving a major airport in the country said that although there did appear to be increased vigilance by the security services, the traveller was still asked on two occasions for "dash", or tips, by airport officials.
Nigerian Information Minister Dora Akunyili has said Nigeria abhors what she called "terrorism in all its forms".
She praised the actions of the father who despite the bonds with his son had sought help from outside his family to try to prevent a possible potential tragedy.
Mr Abdulmutallab Sr was a "courageous and true Nigerian", Mrs Akunyili said.
But the minister condemned the actions of the son as "un-Nigerian".
Reports from within the Abdulmutallab family compound, on a quiet Abuja street lined with middle-class homes, say the family is understandably traumatised and emotionally drained.
Friends say family members are personally horrified by the charges against the 23-year-old and at the same time buffeted by the high politics and blame-games that have been unleashed in Nigeria and the United States - partly as a result of blunders by intelligence agencies.
While the trial of their son looms in the United States, the family are also in the unusually painful position of having his youthful-looking face stare out at them from hourly television news bulletins.
Mr Abdulmutallab Sr is a widely-respected banker. He is now considered by many people in the United States and Nigeria to be a hero for having swallowed his paternal pride and sought help in trying to bring home a wayward son.
But I feel sure that, grieving behind his compound's garden walls, he doesn't feel like a hero.
He had been looking forward to a well-earned retirement.
Now, he may only look forward to pain.