The 19-year-old who made an online threat to shoot a teacher and pupils at a school in Leiden in April has been sentenced to 150 hours of community service.

The threat, made on internet site 4chan, led to all secondary schools in Leiden being shut and put under armed guard.

Janoek V, who was in Costa Rica at the time, told the court the initial threat was sent by an American he met during his trip and who borrowed his laptop. It was sent on a Saturday, saying the shooting would take place the following day, Sunday. V then sent another message altering the day to Monday.

V’s story cannot be verified because the police made no effort to trace the American, news agency ANP said.

The court said it held the youth partly responsible for the original threat because he had lent his laptop and given the American information about the school.

In addition, he had not owned up immediately he heard about the measures taken in Leiden.

V did, however, return to the Netherlands as soon as police traced him to Costa Rica.