Ewold Horn was killed when he made a dash to freedom during a fierce firefight between the Abu Sayyaf militants and army troops in Sulu province's mountainous Patikul town, military commander Brig. Gen. Divino Pabayo Jr. said.
At least six militants were killed and 12 others were wounded in the nearly two-hour firefight, in which eight soldiers were also wounded, the military said. Among those killed was the wife of Abu Sayyaf commander Radulan Sahiron, a militant long wanted by the United States and the Philippines for banditry and assaults.
Pabayo condemned Horn's killing and the militants' "utter disregard for human rights." Government forces "tried our very best to safely rescue him from his captors" and suffered injuries themselves, Pabayo said.
Horn's body was recovered by government forces near a river about 100 meters (330 feet) from the scene of the battle, military officials said. Troops stumbled on the militants while hunting Abu Sayyaf fighters who carried out an attack that killed two children and wounded seven other villagers in a Patikul village about a week ago.
Horn and a Swiss tourist, Lorenzo Vinciguerra, along with Filipino guide Ivan Sarenas were kidnapped by gunmen during a birdwatching trip in the southernmost province of Tawi Tawi, near Sulu, in 2012. Sarenas escaped by jumping into the sea while they were being taken by motorboat to Jolo shortly after they were abducted.
Vinciguerra escaped two years later when he hacked a rebel commander and then was shot and wounded by another militant as he fled in a dramatic escape as government forces were firing artillery rounds toward the militants in Patikul.
Vinciguerra said he asked Horn to join his escape. "I talked to him and asked him to join me, but he refused," Vinciguerra said in December 2014. Although the militants have demanded huge ransoms for hostages in the past, Sahiron kept Horn close by him for years in the hope that military aircraft would not drop bombs on his camps and risk endangering the life of a European hostage, a military official who has helped monitor the militants for years told The Associated Press. The official spoke on condition of anonymity because of a lack of authority to speak about military matters publicly.
Sahiron's emissaries had recently expressed a willingness to hold talks about Horn's fate but demanded that all government forces withdraw from Patikul town before any negotiations, a demand that Philippine authorities could not grant because of the security implications, the official said, without elaborating.
The Abu Sayyaf, an offshoot of the decades-long Muslim separatist insurgency in the south, has been blacklisted by Washington and Manila as a terrorist organization for involvement in kidnappings, beheadings and deadly bombings.
The group was founded in the early 1990s on Basilan island, near Jolo. An unwieldy collective of Islamic preachers and outlaws, it vowed to wage jihad, or holy war, in the predominantly Roman Catholic Philippines, but lost its key leaders early in combat, sending it on a violent path of extremism and criminality.
About 320 armed Abu Sayyaf fighters remain in the south, some of them aligned with the Islamic State group, Sulu military spokesman Lt. Col. Gerard Monfort said.