Philippine prosecutors accused the heiress of a powerful clan with murder Tuesday in the slaughter of 57 people, of whom over half were journalists and officials who accompanied the family and supporters of an election candidate.

At least 10 witnesses that they saw Andal Ampatuan Jr., senior men, including police officers, who blocked motorcade moments before his election rival, the slaughter of 23 November, prosecutor Al Calica told The Associated Press.

Hours later, troops found bullet-marked bodies and cut close to the road, lying on the grass and quickly buried in three mass graves with a backhoe, along with three vehicles. Ampatuan was delivered last week and denied the charges.

He is a scion of a clan allied with President Gloria Macapagal Arroyo, who has ruled the impoverished southern Maguindanao province without resistance for years. His father, the family patriarch, and six family members are also considered suspects, but has not been charged.

Prosecutors originally filed 25 counts of murder against Ampatuan town in South Cotabato, regional court which is closest to the place of slaughter in the town of Ampatuan.

The five prosecutors responsible for the murder case had two boxloads of evidence and statements of witnesses from Manila to Cotabato City on board two Air Force helicopters. Expect to ask the court to try the case in Manila for security reasons.

"The evidence is strong," Calica said, adding that at least 10 witnesses provided written testimony Ampatuan connection with the killing. He said that three of them were in the convoy carrying the journalists and the woman, her two sisters, an aunt and several supporters of rival Ampatuan, deputy mayor of the municipality of Maguindanao's Esmael Mangudadatu Buluan.

Mangudadatu had sent their families to file his candidacy papers for governor. Ampatuan said Mangudadatu had threatened to cut into pieces if you tried to defy the iron grip of the Ampatuan family over the province. Therefore Mangudadatu sent to family members of women in the belief that they would be harmed.

Quote three witnesses, Calica, said he managed to convert their cars from the end of the tail of the convoy and fled after the shooting, and the invaders quickly took control of pickup trucks and sport utility vehicles in the caravan. Police cars were parked along the road and armed men took the victims' vehicles in a remote hillside, where they were slaughtered, Calica said.

Police said they took into custody before the six officers, including police chief of Maguindanao province and his deputy. Two officials, including apparently was seen during the slaughter of Ampatuan said Erickson Velasquez, head of the Division of Criminal Investigation.

Prosecutors said the murders were carefully planned and that more charges will follow. At least one witness said Ampatuan clan had gathered in the courtyard of the patriarch in the capital of the province of Shariff Aguak plan days before the killing, said Chief Prosecutor Jovencito Zuno.