Salvadoran war crime suspect arrested in Mass.

Montano is one of 20 former Salvadoran government officials and members of the military indicted in May by a Spanish court in the slayings of the clergy, their housekeeper, and her teenage daughter, an infamous war crime carried out by the Salvadoran armed forces during the country’s brutal 12-year civil war.

Whether Montano will be extradited to stand trial in Spain in the killings is an open question. A spokesman for the State Department could not be reached last evening for comment.

Despite accusations that he was complicit in one of the most notorious war crimes since World War II, Montano was charged yesterday only with making false statements on an immigration form, a crime that carries a maximum 10-year prison sentence.

He was discovered in Massachusetts by the Center for Justice and Accountability, a San Francisco-based human rights organization that in 2008 filed suit against the 20 defendants in Spain, leading to the new indictments in May.

“We are pleased that US authorities finally acted and arrested Montano, even though the action was only related to immigration fraud,’’ Almudena Bernabeu, a lawyer for the center, said in a statement. “This arrest gives Spanish authorities an opportunity to formally request Montano’s extradition, which, if the US observes, would once and for all result in a trial and justice for this terrible crime.’’

Montano appeared in federal court yesterday in handcuffs, dressed in tan pants, a checkered shirt, and shoes with no laces. He held a cane and took small, unsteady steps. His lawyer, public defender Oscar Cruz Jr., said Montano is recovering from bladder cancer and an infection.

Montano has held a job in Revere since 2003, according to Cruz, though he declined to say where his client worked. Montano lived in Everett with his wife, and he also has a sister in Saugus and a sister in South Carolina, Cruz said.

“He’s just concerned with his family’s safety,’’ Cruz said. Montano also has four children in El Salvador.