Local and international news reports say prosecutor Hans Joerg Stalder argued in court on Tuesday that the three — two Italians and a Swiss — are “criminal tourists” who tried to smuggle explosives into Switzerland to carry out their eco-terror attack. Experts testified at the hearing that the planned combination of fuels and explosive gel could have been deadly.

The three, identified as 35-year-old Costantino Alfonso Ragusa, his 29-year-old wife Silvia Ragusa Guerini and their 26-year-old Swiss friend Luca Cristos Bernasconi, were charged with “planning an incendiary attack on a nanotechnology centre under construction”, and are being tried by Switzerland’s top criminal court.

The three refused to answer questions during the hearing, reports said. Outside the Bellinzona court in the Italian-speaking region of Switzerland, dozens of supporters demonstrated under heavy police surveillance in favour of the defendants and against nanotechnology, biotechnology and nuclear power, reports said.

The accused were arrested on April 15th 2010 with explosives and other components to build a bomb, and have been held in preventive detention since then, according to the Swiss attorney general’s office.  

They also carried with them 31 handwritten letters in German, claiming responsibility for a bomb attack on the IBM nanotechnology facility, on behalf of the “ELF Switzerland Earth Liberation Front,” added the attorney general. The late 2010 bomb attacks on the Swiss embassies in Athens and Rome were also launched in retaliation for their arrest, according to the Swiss Federal Intelligence Service.  

The Earth Liberation Front, born in Britain in the 1990s, is made up of numerous autonomous cells around the world. During congressional testimony in 2004, FBI deputy assistant director John Lewis had said that the group had “emerged as a serious domestic terrorist threat.”  

The targeted IBM nanotechnology research centre, in the small suburb of Rueschlikon near Zurich, focuses on “novel nanoscale structures and devices to advance energy and information technologies,” according to its website.  

A verdict in the case is expected on Friday.