MANILA, Philippines?For the 57th time, the principal suspect in one of the worst massacres in Philippine history, Andal Ampatuan Jr., and 16 others pleaded not guilty Wednesday to the murder charges filed against them in connection with the Maguindanao massacre.

Ampatuan Jr., a former mayor and scion of a politically powerful clan, had already pleaded innocent to 56 murder counts stemming from the Nov. 23 massacre that targeted relatives and supporters of a political rival.

The suspects?among them police officers and militiamen?were returned to a special courtroom inside a maximum security prison in Camp Bagong Diwa, Taguig City, to enter their plea in the case of the last victim, Victor Nunez, a reporter for UNTV channel. The investigation into his death was completed only recently because of delays in identifying his remains.

Ampatuan Jr. is accused of leading more than 100 armed men in an ambush of an election campaign convoy. Thirty journalists were among the 57 shot dead and buried in mass graves near a highway in Ampatuan town.

197 suspects

A total of 197 suspects have been charged with multiple murder counts, including family patriarch and former Maguindanao governor Andal Ampatuan Sr. and other members of the clan that has ruled the impoverished province for years.

Sixty-four have been arrested while the others remain at large.

All those in custody who have been arraigned have denied the charges against them.

One suspect, Chief Insp. Sukarno Dicay, told reporters that a number of them had applied to become witnesses in the case, saying in Filipino that ?if we couldn?t help them [the victims] then, we?ll help them now by speaking out the truth... about what we know.?

?We did not kill [the victims]. We were merely at the checkpoint when the killings happened,? he insisted. ?If the [Department of Justice] would only allow us, our testimony might be the key to uncovering the identity of the [brains] of the massacre.?

His lawyer, Marlon Pagaduan, would not provide details to what his client said, saying the application was still pending and he would not want to jeopardize Dicay?s chances.

After the arraignment, Judge Jocelyn Solis-Reyes, who is handling the celebrated case, set the preliminary conference on Aug. 4 at 2:00 p.m. and the pre-trial conference was scheduled on Aug. 6 at 9:00 a.m.

Motion to inhibit

The judge also acknowledged another motion filed by Ampatuan?s lawyer, Sigfried Fortun, asking her to voluntarily inhibit herself from the case. She ordered the prosecution to comment on this in 10 days.

A private prosecutor noted that this was the sixth attempt of the Ampatuan camp to have the judge removed from the case.

?On the government?s part, we will keep on opposing this,? state prosecutor Juan Paolo Navera told the Inquirer.

Aside from Ampatuan Jr., the other suspects who entered ?not guilty? pleas were Dicay; Inspectors Rex Ariel Diongon and Michael Joy Macaraeg; Police Officer 3 Rasid Anton; Police Officers 2 Hernanie Decipulo Jr., Saudiar Ulah and Saudi Pasutan; Police Officers 1 Herich Amaba, Esprielito Lejarso, Rainer Ebus, and Pia Kamidon, and Takpan Dilon, Esmael Canapia, Muhamad Sangki, Maot Dumla, and Thong Guimano. Miko Morelos and Reuters