Zaldy Ampatuan is one of some 200 people to be investigated
The Philippines' top justice official has reinstated murder charges against two regional leaders over the country's worst massacre in living memory.
Justice Secretary Alberto Agra said new evidence had come to light implicating cousins Zaldy and Akmad Ampatuan.
The men, who deny the charges, belong to a powerful clan allegedly involved in the mass killing of 57 political rivals and journalists last November.
Mr Agra had triggered a public outcry when he cleared the men last month.
He had faced heavy criticism from the families of the victims and prosecutors since the decision
But in a statement on Wednesday, he said new testimony had provided evidence to charge Zaldy Ampatuan, a former governor of Maguindanao province, and his cousin Akmad.
"I am now convinced that there is probable cause," he told reporters.
"The surfacing of a new witness who pinned down Zaldy and Akmad Ampatuan was apparently the result in part of the decisive measures taken by the Department of Justice."
The two accused are brother and cousin of Andal Ampatuan Jnr, a former town mayor and the chief suspect in the massacre on 23 November.
Bodies of the victims were found buried in a mass grave
Mr Ampatuan Jnr, currently on trial in Manila, has denied 41 counts of murder.
Fifty-seven people were killed after their convoy was attacked in the remote region.
They had been on their way to file nomination papers for local politician Ismael Mangudadatu, who is running for the Maguindanao governorship in elections which begin on 10 May.
The body of Mr Mangudadatu's wife was among those later found in a mass grave.
The Ampatuan clan was closely allied to outgoing Philippine President Gloria Arroyo, but since the killings Mr Ampatuan Jr, his father and his brother Zalday have been expelled from her party.
In total, six members of the Ampatuan clan and nearly 200 other people have been investigated for involvement in the killing.
The BBC's Kate McGeown in Manila says that despite the allegations against them, the Ampatuans have not lost their influence in Maguindanao.
Many of them - including some of those currently in jail - are running for political office in next week's elections.