A former Argentine navy lieutenant wanted for prosecution in his homeland for his alleged role in a 1972 massacre of leftist guerrillas has committed no crime and should not be sent back, his attorney told a U.S. judge Tuesday.

U.S. Magistrate Judge Robert Dube said he would issue a written decision in a few weeks on whether Roberto Guillermo Bravo, 68, should be returned to the South American country. Bravo is a naturalized U.S. citizen who has lived in South Florida since 1973.

An Argentine federal judge issued an arrest warrant in February 2008 charging Bravo with 16 counts of murder as well as attempted murder charges. Bravo's attorney says he has done nothing wrong and has already been cleared by a previous Argentine military investigation.

"Most governments don't ask for the extradition of someone who has already been exonerated," Sonnett argued Tuesday.

Nineteen guerrillas were allegedly machine-gunned in their cells at a military base in the southern Argentine city of Trelew in August 1972, days after being recaptured following a prison break, according to Argentine authorities. Three prisoners survived what human rights groups called the "Trelew Massacre" and what they saw as the early seeds of a military "Dirty War" on leftist adversaries.

Bravo, who is free on $1.2 million bail, has denied execution-style killings took place. He has said the Argentine military was waging a justified action against leftist revolutionaries in that turbulent time, and Sonnett said in court papers that Bravo and other military personnel "opened fire in order to defend themselves, repel the attack and prevent an escape."

U.S. prosecutors contend that the guerrillas were slain as they stood with heads bowed in front of their cells.

Dube could block Argentina's extradition request if he finds that Bravo is being targeted for purely political reasons. Sonnett argued in court papers that Argentina's current left-leaning authorities are seeking "revenge" on military officers who fought the leftist guerrillas in the 1970s.

Assistant U.S. Attorney Cynthia Wood argued that Bravo's guilt or innocence should not be decided by a U.S. judge.

"These are issues to be resolved by the Argentine courts," Wood said.

Bravo came to the U.S. shortly after the Trelew events as a military attache and later became an American citizen, according to court documents.

The guerrillas who died were among a larger group that had killed a guard and broken out of a remote prison, with six of them getting away on a hijacked airplane first to Chile and later to Cuba. After an airport standoff, the others surrendered and were taken to the Trelew base where human rights activists say they were subsequently executed. The military had said soon afterward that the guerrillas were killed trying to escape again.

Other former Argentine naval officers suspected in the case have been detained in recent years, including Luis Emilio Sosa, 73, who was accused by Argentine authorities of commanding the naval force that recaptured the guerrillas.

Argentina of the 1970s was marked by leftist guerrilla violence and counterattacks by military forces and death squads as a prelude to a 1976 military coup. Official records show nearly 13,000 people died or disappeared under the 1976-83 dictatorship. Human rights groups put the toll closer to 30,000.