A pilot shuttling between Vancouver and Seattle is being fingered as the "missing link" in the assassination of opposition leader Benigno "Ninoy" Aquino Jr. as The Philippines reopens investigations into one of the worst episodes in the nation’s political history.

The pilot was identified as former Air Force Captain Felipe Valerio by Justice Secretary Raul Gonzalez, who believes believes Valerio is the brains behind the 1983 Aquino assassination.

Gonzalez has now been tasked by President Gloria Macapagal-Arroyo with the search and extradition of Valerio, according to a presidential bulletin posted on the government’s website and entitled, "Manhunt for Aquino-Galman Witness in U.S. and Canada Under Way."

Valerio is believed to have flown to the United States after the Marcos regime was toppled in 1986 and was last known to be working as a commercial pilot using the names Edwin Salvador, Philip Valerio or Philip Valeo.

Gonzalez, who said Valerio was flying back and forth between Washington State and British Columbia, was reported as saying the Department of National Defense (DND) had assured him that it would "try [its] best to give us information as to the latest location of Captain Valerio."

Conspiracy theories have run rife for the past 26 years since Aquino was gunned down on the tarmac of Manila Airport after returning home from exile in the U.S. Everyone from late dictator Ferdinand Marcos and his shoe-loving wife, Imelda, to the U.S. Central Intelligence Agency have been implicated by conspiracy theorists.

Aquino’s murder in 1983 led to widespread street protests that culminated three years later in Marcos’s downfall. Aquino’s widow, Corazon, was installed as president, restoring democracy and redrafting the constitution.

Fourteen military and airport security men were convicted and jailed for their part in the assassination, but no one has ever been charged with ordering the killing.

Even as they walked free this month, the 10 soldiers who were convicted in 1990 over the killing maintained their innocence. Two other soldiers convicted for the murder were freed earlier while two others died in detention.

The Marcos government said Rolando Galman, an alleged communist hit-man, shot Aquino dead and was then killed by the soldiers, but few believe the former dictator’s version of events.

After being freed this month, Ernesto Mateo, an Air Force sergeant who headed the team charged with protecting Aquino, said he wants to meet with the Aquino family and "explain to them personally what happened. Let the Aquino family move to re-open the case. I am willing to meet them and help all of us find the truth," the 57-year-old Mateo said.

Ninoy Aquino’s son, Senator Benigno "Noynoy" Aquino, says the family remains convinced there was a conspiracy behind his father’s murder. While he declined to give any names, Senator Aquino said he agrees investigators should search for Air Force Captain Felipe Valerio, who was then in charge of the Aviation Security Command.

Valerio is believed to be in the U.S., but no-one has ever tracked him down.

Authorities are also looking for another suspect, Romeo Ochoco of the defunct Aviation Security Command (Avsecom), who was believed to have fled to Australia, the justice chief said.

Brigadier General Gaudencio Pangilinan, chief of the Armed Forces’ Civil Relations Service, said they would provide any information they get on Valerio, but admitted they have none as yet.

"Being part of the military, we are duty-bound to provide information [on Valerio], bound to assist, but as of now we have no information," he said.

Public Attorney’s Office head Persida Acosta was quoted in a newspaper as saying: "There will be no closure until Valerio is found."

Valerio was group commander of 805th Special Operations Squadron of the Aviation Security Command (Avsecom). Avsecom members escorted Aquino out of an airplane at what was then the Manila International Airport (now Ninoy Aquino International Airport) before he was shot.

The search for Valerio was renewed after President Arroyo granted clemency to 10 soldiers convicted in the Aquino-Galman case last March 2.

The pardon however did not sit well with the Aquino family. Aquino’s youngest child, television personality Kristina Bernadette "Kris" Aquino, branded it as an "insult" to her father’s memory.

The slain senator’s widow, former President Corazon Aquino, who is suffering from cancer, has long maintained that Marcos himself was behind the murder. During her presidency, however, she did not interfere in the case to avoid accusations of partiality.

Many analysts argue that a cunning political manipulator like Marcos would not be so foolish as to have the hugely-popular Aquino murdered. Marcos was also known to be sick at the time and may have been unaware of what was happening, they say.

Another possible suspect and a key Marcos loyalist, military chief General Fabian Ver, died in Thailand in 1998. Other names mentioned as being behind the killing include prominent Filipino businessmen.

Former solicitor general Francisco Chavez, wrote in his newspaper column: "It speaks volumes of the sordid state of The Philippine justice system that the true author or authors of that grisly crime have remained scot-free and worse, have been allowed to resume political, social and economic relevance."