MANILA, Philippines?Senate Minority Leader Aquilino Pimentel Jr., on Friday urged authorities to arrest the Ampatuan patriarch, Maguindanao Governor Andal Ampatuan Sr., as a "material witness? to the slaughter of 57 people in Maguindanao, saying the latter, too, has a lot of explaining to do in the worst politically-related killing in the country.

This as Senator Miriam Defensor-Santiago urged authorities to amend the multiple murder charges they filed against Datu Unsay Mayor Ampatuan Jr., to terrorism because, she said, the massacre was "an act of terrorism.?

Citing the Human Security Act, Santiago said the perpetrators committed the murders and ?thereby sowing and creating a condition of widespread and extraordinary fear and panic among the populace, in order to coerce the government to give in to an unlawful demand.?

She said that the declared intention of the Ampatuan clan to prevent the Mangundadatu clan from running for governor was ?an unlawful demand.?

Ampatuan Jr., was charged with multiple murder for the death of 57 persons, including the wife and two sisters of Buluan Vice Mayor Esmael Mangudadatu, several journalists and motorists who were stopped in the highway, by armed men believed to be under the employ of the Ampatuans.

In a phone interview, Pimentel said the government was able to make a "good first step? in filing a case against Ampatuan, Jr., the prime suspect in the gruesome murders, but added that officials "should not stop there.?

"I think Governor Andal should be held as a material witness (to the crime),? he said, as he noted that the Ampatuan patriarch, who had not been tagged as a suspect like his son, "has many things to explain.?

There was the backhoe that was found in the mass murder site and used to hastily dig up graves of the victims, which Pimentel noted came from the provincial government of Mindanao.

He also said there were even reports that the backhoe had Governor Andal?s name on it.

There was also the fact that the armed men who committed the mass murders were said to be members of the civilian volunteers? organization of the provincial government, Pimentel also said.

That was why, he said, authorities should also start investigating Ampatuan Sr., by holding him as a material witness and to do so, they should arrest him as well as disarm him.

And to further throw the book at Ampatuan Sr., Pimentel sought the investigation into the Maguindanao governor?s questionable wealth.

"It had been widely reported he was constructing three palaces in Davao City,? he said of Ampatuan Sr., adding authorities should investigate the latter as part of its campaign against corruption.

Meanwhile, Pimentel also said that he will oppose any move by the national government to regain control of the police.

He said he disagreed with Interior and Local Government Secretary Ronaldo Puno?s statements that local executives should no longer have the power to choose the chief of police in their respective areas after the local police there were suspected to be involved in the mass slaughter.

Puno had said he would recommend for Congress to stop such practice by amending the law.

``I disagree because there is no such thing that local executives have absolute power over the police,? Pimentel said.

There was nothing wrong with the law being mentioned by Puno, which he noted was the Reorganization of the Philippine National Police under the Department of Interior and which he said he authored himself.

The law was made during Corazon Aquino?s administration and, according to Pimentel, it was in response to the Martial law practice where the police was placed under the military.

Pimentel said the police was a civilian unit and not a military unit and thus, it was placed under the DILG.

And under the law, it is the national police officials who recommend names of police officials for governors or mayors to choose from, according to the Senate minority leader.

He said there was ``nothing wrong in the selection process except when corruption creeps in.?

``They should just implement faithfully what the law provides,? he said, adding he will oppose any recommendation for Congress to amend the law as he insisted the police was a ``local unit? and thus, was a ``local responsibility.?

In a statement, Santiago said that a complaint for multiple murder was insufficient, because ?the suspects were in effect spitting with impunity at the rule of law.?

But she said authorities probably filed a multiple murder case instead of terrorism because should Ampatuan Jr. be acquitted, he can seek a P500,000 damage for every day he was detained, as provided by the anti-terrorism act.

Santiago suggested for the Department of Justice to complete its preliminary investigation in one month, file the complaint in court and file a motion for the Supreme Court to order a change of venue to Manila ?to avoid a miscarriage of justice,? as provided by the Constitution.

Should Ampatuan be found guilty, he faces a 40-year imprisonment term without parole, according to the senator.

Santiago also called for the investigation of the local police for failure to apply for a written order from the Court of Appeals to conduct surveillance of suspects, to intercept and record the communications of the suspects as allowed by law.

And instead of conducting a public hearing on the mass murder, she said Congress should activate the Joint Oversight Committee on Antiterrorism, which has its own independent counsel.