Prosecutors in the Philippines said Tuesday they have filed 25 counts of murder against the heir to a political clan accused of leading the election-related massacre of 57 people last week.
On Friday, authorities charged Andal Ampatuan Jr., a town mayor in Maguindanao province, with mass murder.
Authorities flew him to Manila from the southern Philippines, where he turned himself in the day before.
Ampatuan is suspected of planning the attack on a rival politician's convoy of relatives, supporters and journalists.
A convoy was traveling to register politician Ismael Mangudadatu as a candidate for provincial governor, when about 100 gunmen attacked and slaughtered the occupants. The dead included Mangudadatu's wife, sisters and 29 journalists.
Philippine authorities also placed eight other members of the Ampatuan clan under investigation, including the mayor's father, Andal Ampatuan Sr., who is Maguindanao's current governor. The suspects are barred from leaving the country.
Hundreds of journalists and activists marched in the Philippine capital Monday to protest the massacre.
Wearing mostly black shirts, the crowd heckled the president's press secretary Cerge Remonde, who crossed a police line near the presidential palace in Manila to assure the journalists the government is seeking justice.
In another move, the Philippine military removed two senior commanders based in the south from their posts, for suspected security lapses related to the massacre. The general and colonel also were placed under investigation.
Some information for this report was provided by AP and AFP.