A German couple was found dead Thursday on a cattle farm in northern Paraguay, apparently at the hands of a guerrilla group that earlier this week demanded the owner of an adjoining farm pay $300,000 and give food to the poor.

Roberto Natto, 60, and Erika Reiser, 53, had been taken away Wednesday along with four workers on their farm outside Yby Yau, about 395 kilometers (245 miles) north of the capital, investigator Sandra Quinonez said.

According to workers who managed to get free, "the captors wore camouflage uniforms and were apparently directed by Esteban Marin, a member of the criminal Paraguayan People's Army," Quinonez said Thursday.

Both of the Germans were shot in the back with a handgun, Quinonez said. She said agents found the bodies after a shootout with guerrillas in the area.

Interior Minister Francisco de Vargas said the two might have been killed because their captors had to flee and the advanced age of the couple made it difficult to take them. The leftist group often kidnaps people for ransom.

The bodies were taken to the capital, Asuncion, and were to be returned to Germany.

Quinonez said the Germans' farm, Luisa Ganadera, is adjacent to La Gringa, where guerrillas on Sunday burned two tractors and a building that housed workers. The group left a hand-written note demanding that the owner, Osvaldo Dominguez Dibb, pay a $300,000 "fine" and distribute free beef in several neighboring communities as punishment for alleged deforestation.

"Nature is not ours, it's only borrowed from future generations," read the note, published by local news organizations.

The rebel group gave Dibb until Feb. 6 to meet its demands, said Gen. Ramon Benitez, commander of a military anti-terrorism group. "The family of the cattle farm has not yet made a decision whether it will comply or not," he told The Associated Press.

Dibb is a former president of popular Paraguayan soccer club Olimpia and has stakes in several businesses.

The guerrilla group, operating in remote jungle areas, has frequently attacked farms along with military and police posts. Since 2008, its attacks have killed at least three members of the military, 13 police officers and 26 civilians.