The trial has begun in Germany of one of the two main suspects accused of attempting to bomb two regional commuter trains in July last year.
Hajdib's lawyers said he designed the devices not to explode
Youssef Mohammed al-Hajdib, 22, accused of attempted murder, was found guilty in absentia in his native Lebanon just before the start of the trial.
He got a life sentence, while second suspect Jihad Hamad - who had fled back to Lebanon - was jailed for 12 years.
The bombs did not go off, but could have caused carnage, prosecutors say.
The two men planned the attacks after becoming incensed by caricatures of the Prophet Muhammad in European newspapers, prosecutors added.
At the start of Hajdib's trial in Dusseldorf, German prosecutors said the pair had planted identical suitcases containing propane gas and crude detonators on two trains in Cologne.
Prosecutors accused Hajdib of planning the attacks with Hamad in an attempt to "kill an undetermined number of people".
The men were detained after police released CCTV footage
"A detonation would have in both cases led to a significant wave of pressure; lighter fluid in the 'bomb trolleys' could have set off a fireball," AFP news agency quoted the charge sheet as saying.
A lawyer for Hajdib said his client had deliberately designed the devices so they would not explode, adding that he was "not a dangerous terrorist".
"Perhaps they just wanted to send a message," said Bernd Rosenkranz, quoted by AFP.
Hajdib was arrested at the main rail station in the Baltic Sea port city of Kiel in August 2006 after police made closed circuit TV footage of the two suspects public.
A note written in Arabic, a telephone number in Lebanon and packets of starch with labels in Arabic and English were found alongside the devices.
The identical suitcase bombs were fitted with timers set to go off 10 minutes before the trains arrived in Dortmund and Koblenz respectively.
Police said they failed to detonate because of a construction flaw.
Hamad, who fled to Lebanon and gave himself up to police last year, admitted helping to plant the bombs.
Three other men on trial in the Lebanese capital Beirut were acquitted.