A preliminary investigation into a Swiss citizen who worked for the Blackwater private security firm in Iraq has closed.
A military court will now decide whether the person in question, referred to by Swiss television only as "Mike", acted as a mercenary.
A conviction for any person serving in a foreign military can result in up to three years' imprisonment or a fine.
The case is regarded as precedent setting within the Swiss military justice system because the accused served in a private company rather than under another flag.
In previous cases, people had been convicted after serving in the French Foreign Legion.
Blackwater is one of the largest security contractors in Iraq. It employs more than 1,000 people there, but also received contracts for policing New Orleans following Hurricane Katrina in 2005.
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