who ordered the assination of senator benigno aquino jr?

Answer 1

His political opponents.

Answer 2

It was not determined who really mastermined the assassination of Senator Benigno Aquino Jr. although there were assumptions that Marcos was the one responsible.

On August 21, 1983, while on his way to Manila, Ninoy was accompanied by several foreign journalists to ensure his safety or, in the least, record events for posterity in case rumors of a planned assassination proved to be true. Despite a convoy of security guards (all assigned to him by the Marcos government) and a contingent of 2,000 military and police personnel on the tarmac, he was fatally shot in the head as he was escorted off the airplane. Government investigators claimed that he was gunned down by Rolando Galman, who was immediately shot dead by the aviation security. No one actually identified who pulled the trigger, but Rebecca Quijano, another passenger, testified that she saw a man behind Aquino (on the stairs) point a gun at the back of his head, then there was the sound of a gunshot. Post-mortem analyses disclosed he was shot on the back of the head in close range with the bullet exiting at the chin, an angle which supports Quijano's testimony. Even more suspicions arose on who ordered the execution when Quijano described the man as wearing a military uniform.

Everyone from the CIA to the Communist Party of the Philippines to First Lady Imelda Marcos was accused of conspiracy. President Marcos was reportedly gravely ill, recovering from kidney transplant when the incident occurred. Theories arose as to who was in charge and who ordered the execution. Some hypothesized that Marcos had a long-standing order for Aquino's murder upon the latter's return.

The Marcos government then ordered an independent body, the Agrava Commission, to investigate. The men on the tarmac, the rank and file of the military, were found guilty and are currently serving life sentences at National Bilibid Prison. They have recently filed an appeal to have their sentences reduced after 22 years, claiming the assassination was ordered by a Marcos crony and business partner (and Corazon Aquino's estranged cousin), Eduardo Cojuangco Jr., who was eventually cleared by the Aquino family.

Aquino's funeral procession on August 31 lasted from 9 a.m.--with a funeral mass officiated by the Catholic archbishop of Manila, Jaime Cardinal Sin, and held at Santo Domingo Church--to 9 p.m., when his body was interred at the Manila Memorial Park. Two million people lined the streets during the procession which was aired by the Church-sponsored Radio Veritas, the only station that covered the procession. The procession reached Rizal Park, where the Philippine flag was brought to half-mast.