Doug Stanglin

USA TODAY

Miss Honduras and her sister were shot to death in an "act of passion" by a jealous boyfriend at a birthday party and buried in a river bank in the mountains, police said Wednesday.

Maria Jose Alvarado, 19, who won her title in April, and her sister, Sofia Trinidad Hernandez, 23, went missing last week only three days before they were to leave for London for the Miss World competition.

Gen. Ramon Sabillon, the Honduras National Police director, said Sofia's boyfriend, Plutarco Antonio Ruiz, 26, had confessed to the killings and led authorities to the bodies.

They were found near a river in the mountainous region of Santa Barbara, in northwest Honduras, where Alvarado had grown up and had worked as a department store model.

Ruiz and an alleged accomplice, Aris Valentin Maldonado, were arrested in connection with the killings, police said, according to the newspaper La Prensa.

Alvarado and her sister were attending a birthday party for Ruiz Thursday night at a local spa when he allegedly became angry that Sofia was dancing with another man, according to witness statements, Sabillon said.

He allegedly shot Sofia to death then killed Alvarado when she tried to flee. Sabillon called the killings an "act of passion" inflamed by jealousy.

The police official said Ruiz and the alleged accomplice, Aris Maldonado, admitted burying the bodies near the river so they would decompose quickly. Police said the killers then went back and tried to clean up the crime scene, according to La Prensa .

Leandro Osorio, head of the National Directorate of Criminal Investigation, said two firearms and a pickup allegedly used to transport the bodies were confiscated, the newspaper La Tribuna reports.

Teresa Munoz, mother of the victims, said Ruiz, acting nervous, had called her the morning after the two women disappeared and claimed they had left the party in a car with some other people.

"They were not very astute about assessing the people around them. They were just friendly," Munoz told Televicentro. "They were taken out by people they hadn't known very long."

Julia Morley, chairman of the Miss World Organization, said the group was "devastated by this terrible loss of two young women, who were so full of life," Reuters reports.

The organization would say prayers for the dead women in a service on Sunday and hold a fundraiser to donate money for a children's home in Honduras chosen by their mother, she added. Because of the tragedy, there will be no entrant from Honduras at the pageant.

Honduras, overrun with streets gangs and drug-trafficking, has the highest murder rate in the world for a country not in war, with an estimated 90 to 95 killings per 100,000 people.

It is one of Latin America's poorest countries and earlier this year was the main source of a surge in unaccompanied minors migrating to the United States, many to escape the violence.

Contributing: Associated Press