As police raid properties across the country following Monday's terror attack, a parallel search is stretching back in time, to piece together the life of the suspected bomber.
Salman Abedi was named on Tuesday but his motivation remains a mystery. Slowly, however, a jihadi jigsaw is falling into place, a timeline which might eventually allow us to understand how a man raised in Manchester could commit such an abominable atrocity against his home city.
We know his parents came here from Libya, and there are suggestions that his father was part of an al-Qaeda-linked militant group. More recently, we know he went to Libya, and officials in France claim he also went to Syria - a trip which appears completely inexplicable if not undertaken for the purposes of terror training.
But perhaps the crucial piece in the jigsaw is a visit to Dusseldorf, reportedly made by Abedi just days before he detonated his explosive device in the foyer of Manchester Arena.
Dusseldorf is known as a hotbed for radical Islam, and many cases of extremism have been reported there. If Abedi wanted to finish off his training, or get some final instructions, in a European city, Dusseldorf would have been an ideal option.
Reports state that there are at least 55 mosques in the state of North Rhine-Westphalia, of which Dusseldorf is the capital, with a known history of radical Islamic ideology. Anis Amri, the man who attacked Berlin Christmas market in December, had lived in North Rhine-Westphalia and been in contact with radical Islamic preachers in the state before he drove a lorry into a packed Christmas market, killing 12 people.
Amri is believed to have liaised with radical preacher Abu Walaa, who has been described as Islamic State's top representative in Germany. Walaa, who has previously been arrested for recruiting people to fight in the Middle East, is known to have many connections with preachers in North Rhine-Westphalia.
Aside from Walaa, terror analysts claim there is a large Islamist cell based in Dusseldorf, which may have been led by a top al-Qaeda terrorist called Atiyah Abd al-Rahman. Perhaps unsurprisingly, it was the scene of a major terror trial in 2012, when four suspected al-Qaeda members were said to have been planning a shrapnel bomb attack, and last year it was the target of a major terror plot which was only foiled by police at the last minute.
Four suspected Isis militants from Syria were arrested when police discovered the plot, with prosecutors saying three of the four men had been directly commissioned by the leaders of the terror group to carry out the massacre.
Their plot may have been foiled, but sadly it seems this particular bust only chiselled away the tip of the iceberg. In March last year Burkhard Freier, head of domestic intelligence in North Rhine-Westphalia, said he had recorded more than 100 cases of extremist groups linked to Salafism in the state.
Freier claimed the groups tend to target young boys who are in the country alone - a category which Salman Abedi would certainly fall into. A vulnerable young man who reportedly chanted Islamic prayers as he walked down the street, Abedi would appear the ideal mark for a sharp-eyed jihadi recruiter - and the melting pot of Dusseldorf would appear to be the perfect finishing school for a would-be militant.