Police in Lebanon and southern Germany on Friday arrested the third and fourth suspects in connection with the failed plot to blow up German passenger trains.
Two suspects have already been arrested in connection with the plot
Federal prosecutors in Karlsruhe said that the third suspect, arrested in the southern German city of Constance on Friday, moved in the same circle as Youssef Mohamad El Hajdib, the 21-year-old Lebanese man who was arrested in Kiel on Saturday as he was apparently trying to flee the country.
The prosecutor's office said it was not yet clear "if and to what extent" the suspect in Constance was involved in the failed plot to set off bombs on trains in Dortmund and Koblenz last month, but that police were searching the man's student residence.
Also on Friday, Lebanese authorities arrested a fourth suspect, identified as a 24-year-old Lebanese man with the initials K.H.D. His arrest was based on information provided by Jihad Hamad, another suspect who had turned himself in to Lebanese authorities on Thursday, a senior Lebanese judicial source said. The source gave no further details.
Second suspect questioned in Lebanon
Meanwhile, investigators are hoping that more of their questions about the plot will be answered following Hamad's interrogation, at which officials from Germany's Federal Criminal Police Office (BKA) are present.
"We're confident that he will break his silence and that we'll know much more later in the day," BKA President Jörg Ziercke told public broadcaster ARD on Friday morning.
Both Hamad and El Hajdib were identified on security camera footage dragging suitcases loaded with crudely made bombs onto trains in Cologne.
Did they have help?
While investigators and political leaders have been pleased about the quick succession of arrests, big questions remain about the case, including whether the men were working alone or had the support of a terrorist network.
Ziercke says it's too early to say if the men belong to an international terrorist network
Ziercke said it is still too early to say if they belonged to an international network.
"We assume that this concerns a terrorist group here in Germany, which is also the view of the federal prosecutors," he told German broadcaster n-tv.
"We know that the suspects had accomplices. At the moment we're trying to determine whether this was an international network or if it was an autonomous terrorist group in Germany."
German terror expert, Elmar Thevessen, has pointed out that Hamad and El Hajdib lived hundreds of miles apart, raising the question of how they were able to communicate and gain each other's trust. According to testimony from El Hajdib, the two men first met in Germany.
"We know from Jihad Hamad, who gave himself up, that he only arrived in Cologne in February of this year, just five months before the crime," Thevessen said. "Where did the contacts come from and how could he so quickly get himself set up to prepare an attack that almost succeeded?"
Searches of Hamad's apartment have turned up damning evidence, including DNA that matches that on the suitcases, as well as receipts for the gas canister and gas used in the failed plot.
The plot has reminded Germans that they are not immune to international terrorism. Wolfgang Bosbach, a domestic policy expert for Berlin's conservative CDU/CSU parliamentary group, has warned that there are an estimated 32,000 Islamists in Germany and some 3,000 of these were considered extremists. That, he said, represents a "considerable threat potential for our country."