TRAUNSTEIN, GERMANY (Reuters) - A German court sentenced three Syrian men on Friday for running a smuggling ring from Turkey to Europe over the deaths of 13 migrants in the Mediterranean two years ago.

The migrants drowned after their dinghy collided with a freighter off the Greek island of Lesbos in September 2015.

The court sentenced the main suspect to four years in prison and the man who piloted the dinghy two and a half years in prison. A third man, who liaised with the refugees’ family members in Germany, was given two years on probation.

Prosecutors had accused the three, who had come to Germany as refugees from their country’s civil war, of operating a smuggling network that resulted in deaths. In German judicial practice, the names of defendants are not usually made public.

The U.N. refugee agency says that 118,523 migrants have reached Europe by crossing Mediterranean so far this year and estimates that 2,420 have died or are missing. In all of 2016, it says 362,753 migrants arrived by sea.

In Germany, migration and security are big issues in a campaigning for parliamentary elections on Sept. 24.

Chancellor Angela Merkel is widely tipped to win a fourth term despite tensions about her decision in August 2015 to open the door to more than one million migrants.