RUTHFULLY YOURS

It’s hard to know who had most to gain—and the least to lose—from the death of Argentine federal prosecutor Alberto Nisman. I’d say it’s Iran.Nisman was scheduled to testify last week to the Argentine Congress about his investigation into the 1994 bombing of a Buenos Aires Jewish community center that killed 85. In 2006 he indicted seven Iranians and one Lebanese-born member of Hezbollah for the crime. None have been captured, though the Lebanese suspect was killed in 2008 in Syria.

Earlier this month Nisman filed a criminal complaint in an Argentine court, alleging that President Cristina Kirchner and Foreign Minister Héctor Timerman had crafted a secret agreement with Iran to let the terrorists off the hook in exchange for Iranian oil largess and Iranian purchases of Argentine grain.

Nisman claimed he had a solid case against la presidenta and her alleged co-conspirators, and he released a summary of a 300-page report on his investigation. He promised to reveal more at the hearing.

But his objective was never to bring down the president. He sought justice for the bombing victims, and on Jan. 14 he spoke of a new plan to secure it on the Argentine television program “A Dos Voces.” “It’s close to coming out,” Nisman said, “and I say close because I’ve already made the decision, and we are making final revisions. There is a way for the Iranians to be extradited . . . [so] that [they] face trial in the Republic of Argentina.”

Less than a week later the prosecutor turned up dead. His body was found the night before the Jan. 19 hearing in the bathroom of his Buenos Aires apartment with a single .22-caliber bullet through the head.

It took almost no time for President Kirchner’s secretary of security, Sergio Berni, to arrive at the apartment and declare the cause of death an apparent suicide.

There has since been only confusion. First came word that the service door to the apartment was locked from the inside; then a locksmith called to the scene contradicted that. First there were only two ways into the apartment. Then investigators announced there is a third, and that recent footprints were found in that narrow corridor. First it was suggested that the test for gunpowder on Nisman’s hands was important. When the test for gunpowder was negative, it was dismissed as unimportant because, well, that can happen with small bullets. Countless questions remain, including why his bodyguards reportedly were not on watch in front of his door and why the journalist who broke the news that he was found in a pool of blood fled the country over the weekend.

The lead investigator in the case has not issued a final ruling, and those who knew Nisman say the suicide theory stretches credulity. He had spent 14 years on the bombing case and was about to march into Congress with two years of judicially approved wiretaps that he believed would expose a game of footsie between Mrs. Kirchner and Tehran.

Nisman was in good spirits about the matter, as indicated in his TV appearance. He was divorced, but by all accounts close to his teenage daughters. It seems unlikely that he would have pulled the trigger without leaving them so much as a farewell note. His ex-wife, who is an Argentine judge, says she does not believe he committed suicide.

Argentines smell a rat, not the least because the kirchneristas have earned a reputation for corruption and coercion, and this looks like a mob hit. Late last week even Mrs. Kirchner seemed to realize that the suicide narrative wouldn’t fly. After remaining silent for days, she announced her own theory: Nisman was murdered by rogue members of the Argentine intelligence service who are trying to bring her down.

These enemies, she said, concocted the story that she and Mr. Timerman had made a deal to receive oil and sell grain in exchange for providing impunity to the terrorists. The secretary of the presidency backed her up. Nisman “could not have written this nonsense,” he said. “It is totally clear he had nothing to do with it, but there were people around him who had a different agenda.”

Of course the way to learn whether Nisman was driven to kill himself, or whether he was killed by disloyal spies who used him, would be to air every detail of his report. If she really wants to get to the bottom of things Mrs. Kirchner will name and support a new, independent prosecutor. But that might get her into trouble with Iran.

If Nisman was murdered, it involved a level of sophistication not normally associated with Argentina but not uncommon for Iran. Tehran has more than 40 years of experience knocking off meddlesome individuals abroad and is now trying to allay global distrust as it bamboozles Barack Obama about its nuclear-weapons program. Nisman’s search for truth may have put a target on his back.

Write to O’Grady@wsj.com