Fourteen men have gone on trial in the Netherlands charged with belonging to a radical Islamist terror network.
Bouyeri is alleged to be a key member of the "Hofstad" group
Among the accused is Mohammed Bouyeri, already jailed for life for the murder of film-maker Theo van Gogh last year.
The trial, the first to come to court under new anti-terror legislation, is being seen as a test case.
The suspects are alleged to be members of the so-called Hofstad group, based in The Hague. Two are also charged with trying to kill police with a grenade.
Another of the men is accused of weapons offences after being arrested in Amsterdam last year with a loaded gun.
A court ruled in November that 27-year-old Bouyeri could stand trial a second time despite being given a life sentence in July. He confessed to killing Van Gogh - a critic of radical Islam - out of religious conviction.
Bouyeri is alleged to have played a key role in the Hofstad network, hosting meetings of the group in his Amsterdam home and spreading radical texts.
In court on Monday a 17-year old girl viewed as a key witness refused to answer questions about her ex-boyfriend, one of the co-accused.
The girl, known as Malika, sat in silence as prosecutors read parts of her statement to police, in which she says she watched al-Qaeda videos with her boyfriend and knew of plans to attack a shopping centre.
Malika was dressed in Islamic dress with only her face visible, and prosecutors said she had been intimidated into staying quiet. Defence lawyers denied the charge.
Prosecutors are using new anti-terror laws, brought in last year, which introduced a charge of "membership of a criminal organisation with terrorist intent".
If found guilty, the men face jail sentences of up to 15 years.
The BBC's Geraldine Coughlan in The Hague says the new legislation may help prosecutors, who have suffered setbacks in recent terror trials.
There is now more scope for them to build terrorist, rather than criminal, charges and for the defence to challenge evidence from the intelligence services, our correspondent says.
The trial started on Monday morning in a high-security court in Amsterdam known as "the bunker". It is expected to last at least two months.
Dutch teenager Samir Azzouz was cleared earlier this year of plotting attacks on Amsterdam airport, government buildings and a nuclear reactor after a court ruled there was no direct evidence.