MADRID (Reuters) - A Spanish court has ordered the imprisonment of a former El Salvadoran army colonel for participating in the murder of five Spanish Jesuits in 1989 during the Central American country’s civil war, a court ruling showed on Thursday.

The ruling comes after the United States deported Colonel Inocente Orlando Montano Morales to Spain, where he is facing charges related to the massacre of six Roman Catholic priests. He arrived in Madrid on Wednesday and was taken into custody.

Montano, who is being prosecuted for murder and crimes against humanity, will formally be notified of his charges next Monday, according to the ruling from the Spanish High Court.

Montano, 74, had been in U.S. custody since 2011 when he was arrested outside Boston on immigration fraud charges after the Spanish government indicted 20 former Salvadoran army officers for the killings of the Jesuit priests, their housekeeper and her daughter.

The group was targeted because one of the priests, Father Ignacio Ellacuria, was a prominent critic of the U.S.-backed right-wing government. The massacre was one of the most notorious acts of a decade-long civil war during which 75,000 people were killed and 8,000 went missing.

Spanish judge Manuel Garcia Castellon said in his ruling on Thursday that Montano “actively participated in the decision and design of the murder of the Spaniards and Jesuits of an El Salvadoran University, Ellacuria, Ignacio Martin, Segundo Montes, Amando Lopez and Juan Ramon Moreno.”

Montano, who has proclaimed his innocence, is also accused of overseeing a radio station that urged the priests’ murder and participating in meetings a day before the deaths when a colleague gave the order to kill the men.

The massacre occurred early on Nov. 16, 1989, when a group of soldiers from the U.S.-trained Atlacatl Battalion entered the campus of the Central American University where Ellacuria was rector. At the time, a battle was raging across the capital San Salvador as part of a nationwide offensive launched by the left-wing Faribundo Marti National Liberation Front (FMLN).

Ellacuria had advocated a negotiated settlement to the war and the international revulsion at the murders helped to push through such a solution.

The war ended in 1992. After a criminal investigation, two army officers were convicted for the Jesuit murders and jailed, but later released after an amnesty law passed in 1993.