In a decision penned by Associate Justice Minita Chico-Nazario, the high court granted the prosecutors bid to exclude Superintendent Glen Dumlao as a suspect and make him a state witness instead.
Dumlao had implicated Aquino, Mancao and several other police officers in the disappearance and murder of Dacer and his driver, Emmanuel Corbito in November that year.
All four are members of the defunct Presidential Anti-Organized Crime Task Force once headed by Sen. Panfilo Lacson, a former Philippine National Police chief.
No formal charges, however, were filed against Aquino and the others pending final resolution of the petition regarding Dumlao.
The SC ruling reversed a Court of Appeals decision that denied a prosecution petition seeking Dumlaos inclusion in its roster of state witnesses.
However, it excluded three other individuals Alex Diloy, Jimmy Lopez and William Lopez from the complaint as suspects. They are now state witnesses.
The SC overturned the Court of Appeals ruling that Dumlao may not be admitted to the governments witness protection program because he was a police officer and, therefore, may not become a state witness.
The SC said there was nothing in the law that bars a police officer from admission into the justice departments Witness Protection Program (WPP).
"Admission to the WPP and being discharged as an accused are two different things. Dumlaos being a law enforcement officer, thus disqualified to be under the WPP, do not in any way prohibit him to be discharged from the information," the ruling stated.
The ruling was issued barely two months before the fifth anniversary of the high-profile murders.
Dacer was a publicist of former President Fidel Ramos. It is believed that he was silenced to prevent him from exposing corruption in the administration of then President Joseph Estrada, who was facing an impeachment bid at the time.
He and Corbito were abducted on Nov. 24, 2000 in broad daylight along the Osmeña Highway (formerly South Superhighway) in San Andres, Manila while Dacer was on his way to work.
Their charred remains were discovered months later in a remote barangay in Indang, Cavite. Forensic investigation showed that the bodies were burned after the two had been strangled to death.
They were kidnapped as they waited for a traffic light at the intersection of Osmeña Highway and Zobel street in Manila.
Also accused in the kidnapping are Chief Inspector Vicente Arnado, SPO3 Jose Escalante, SPO1 Rolando Lacansandile, Inspector Roberto Langcauon, SPO1 Ruperto Nemeno, SPO1 William Reed, SPO1 Mario Sarmiento, PO2 Thomas Sarmiento, SPO4 Marino Soberano, SPO4 Benjamin Taladua, SPO3 Mauro Torres and Inspector Danilo Villanueva.
Arrest warrants for Aquino and the others may soon be issued following the Supreme Court decision, said Ricardo Diaz, head of the National Bureau of Investigations Interpol division.
However, bringing Aquino to justice may be a challenge because he is currently facing espionage charges in the United States.
Aquino and Leandro Aragoncillo, an analyst of the Federal Bureau of Investigation, were arrested last month for espionage by the FBI.
Aragoncillo allegedly stole classified information from the office of Vice President Dick Cheney at the White House and the FBI.
He allegedly passed them on to opposition politicians in the Philippines.
Aquino was recently indicted by a federal grand jury on charges of passing classified information from Aragoncillo to current and former officials in the Philippines opposed to President Arroyo.
Malacañang suspects that the stolen information was being used in an opposition coup plot. With Evelyn Macairan