MANAGUA (Reuters) – Eddy Montes, a protestor shot dead in a Nicaragua prison this week, was a naturalized U.S. citizen who served in the Navy, but ultimately returned to the Central American country where he fought for a change in government, his family said. Montes died on Thursday after he and other prisoners tried to snatch a gun from a guard while the International Red Cross was visiting the prison, the Nicaraguan interior ministry said, adding that the guard acted in self-defense. He had been jailed after protesting against Nicaraguan President Daniel Ortega in October last year, during protests that have killed at least 300 people. The protests erupted over welfare benefits but spiraled into a broader movement to oust Ortega, who is serving his third term as president. Angered by Montes’ death, opposition groups said on Friday that they would stage new protests over the weekend. The U.S. State Department condemned his death as a killing at the hands of Nicaraguan riot police and urged the government to thoroughly investigate the incident. It also called for other political prisoners to be released. “The lack of justice for these prisoners and for the hundreds of innocent civilians killed by Ortega’s security and parapolice forces shows the regime’s utter disregard for human life and democratic freedoms,” it said in a statement. The Nicaraguan government prohibited the demonstrations in November last year and have accused the protesters of intending to cause chaos. Montes had spent much of his childhood and young adult years in the United States, family members say, but returned to Nicaragua in the early 1980s to study medicine. Ortega and his leftist Sandinista party had came to power a year earlier. In 1984, Montes organized a protest after the Sandinista government passed a law to introduce military service. Gloria Montenegro, his wife of 18 years, said his activism had put him on the radar of the government. “With those anti-government protests, he became a target [for the government],” Montenegro said, recalling a time during the Cold War when dissidents were backed by the United States and the Nicaraguan government by the former USSR. “So we fled to Costa Rica and after that to the United States, where he decided to join the U.S. Navy.” Montes was based out of San Diego. Later, he worked in real estate. Montes returned to Nicaragua in 1993 and bought farmland in his native Matagalpa. It was not long until he joined anti-government protests again. “He was always seen as an opponent,” said Yader Valdivia, an attorney who once worked with the Nicaraguan Center for Human Rights and is now in exile in Costa Rica. “When the protests began, he began to help by bringing in food, supplies and medicine to the students.” Jafet Montes, his daughter, who lives in California, said Ortega should be held responsible. “I blame the government, I blame the president, because he controls everything that happens in that country,” she said.