An appeals court in Costa Rica has ordered a new trial for a man convicted in the killing of a McLouth High School student visiting the country on a Spanish Club trip two years ago.

Justin Johnston was 16 when he was fatally wounded in an overnight shooting outside a Costa Rican hotel in June 2011. He had reportedly been mistaken for an intruder and shot by a hotel security guard. The guard, Jorge Guevara, was convicted in the killing and sentenced to 15 years in prison last year, but that verdict has been overturned and a new trial is set for September.

A Sentencing Appeals Court in San Ramón, Alajuela, northwest of the capital, ruled in favor of an appeal filed by Guevara’s attorney that claimed “the original trial court did not establish Guevara’s intent to kill Johnston,” according to The Tico Times, a San Jose, Costa Rica, newspaper. In addition to the prison sentence, the trial court had also ordered Guevara and the hotel, La Cangreja, to pay $650,000 in restitution to Johnston’s family.

When he was killed, Johnston was in La Fortuna de San Carlos, Costa Rica, on a nine-day McLouth High Spanish Club trip with 12 students and two school district sponsors. In the early-morning hours of June 2, 2011, he and another student left the hotel and returned after curfew, according to the Tico Times. When they returned, the pair passed close to an adjoining property with a barbed-wire fence to avoid being noticed. Police said the guard fired a warning shot into the air, frightening the teenagers, who began running toward the hotel. The guard fired in the direction of the students and fatally wounded Johnston, the newspaper said.

Guevara’s gun was unregistered, police said. During the trial, the guard said his intent was to send a second warning shot because he thought the youths were thieves.

Johnston had just completed his sophomore year at MHS before heading to Costa Rica. After his death, Johnston’s parents started the Remembering Justin memorial fund, which has raised money for $1,000 renewable college scholarships for McLouth high school students. The family posts regular updates about fundraising efforts for the charity on the Facebook page Justice for Justin.

Johnston’s death marked the second time a northeast Kansas student was killed while on an educational trip to Costa Rica. Shannon Lucile Martin was only a few days from graduating from Kansas University in May 2001 when she was murdered in Golfito, Costa Rica, while walking to her residence after a night out at a disco. She had been in Golfito finishing a class project to collect rare fern samples.