A human rights organization claimed on Tuesday that an Iranian-American man had been hanged by the Islamic regime for committing murder in California.

The report could not be independently verified and it remains unclear if the man was an American citizen, as he had not been listed among any of the known U.S. prisoners being held in Iran.

"According to confirmed sources, Iranian authorities carried out the death sentence for Hamid Samiee and another prisoner at Karaj's Rajai Shahr Prison on Wednesday November 4," Iran Human Rights, a nonprofit organization that claims to have sources within Iran, disclosed on Tuesday.

"Samiee, reportedly accused of committing an act of murder in California, was arrested by Iranian authorities upon his return to Iran," according to the organization's report. "He was sentenced to death by Branch 71 of Tehran's Criminal Court for the murder of an Iranian man identified as Behrouz Janmohammadi."

"Confirmed sources say Samiee was arrested in 2008 after the murder victim's family had reported him to Iranian authorities," according to Iran Human Rights.

Samiee and Janmohammadi were reportedly friends living in Californian until an altercation took place between them, according to sources who spoke to the human rights organization.

"Hamid and Behrouz were friends in California until they were involved in an altercation that resulted in Behrouz drawing a knife on Hamid; and Hamid exercised self defense, which resulted in Behrouz's death," the group reported, citing "an individual close to Samiee who asked to be anonymous."

"Following the incident, Hamid managed to make his way back to Iran where he was arrested by authorities just a few months after his arrival," the source continued. "Hamid endured extreme torture and was forced to confess against himself; and a lot of his confessions were false."

The organization claims that Iranian officials "extracted forced confessions" from Samiee and refused to believe that had acted in self-defense.

"All they cared about was that Hamid confessed the way they instructed him to," according to the source who spoke to Iran Human Rights.

Samiee's family is reported to have visited the Swiss Embassy in Tehran to meet with two individuals purportedly responsible for "protecting the interests of the U.S. in Iran."

One of these representatives, an individual referred to in the report only as Mr. Meyer, "reportedly informed the relatives that he would personally look into Samiee's case and will coordinate his efforts with the US Department of State."

A State Department official did not immediately respond to a request for comment and information about the credibility of the report.

Iran Human Rights did not respond to a request for more information. The Los Angeles Police Department also did not immediately respond to a request for comment.

UPDATE 1 December, 2015, 1:04 P.M.:

A State Department official told the Washington Free Beacon Tuesday afternoon that Samiei is a dual citizen and that it is looking into the reports on his hanging.

"We are aware of reports of the execution in Iran of a dual citizen, Mr. Hamid Samiei," said the State Department official, who was not authorized to speak on record. "We do not yet have official confirmation of his death and are seeking more information."

The State Department has been aware of Samiei’s plight since late October, the source said.

"This case was brought to our attention on October 28, immediately after the Foreign Interests Section at the Swiss Embassy in Tehran was notified of Mr. Samiei’s impending execution," the official said. "We are not aware of any notification to the Department of State or the Swiss Foreign Interests Section of Mr. Samiei’s arrest, sentencing, or imprisonment prior to October 28. Iran does not recognize dual nationality."

The Iranians often leave the State Department in the dark when it detains dual nationals, the source said.

"The Iranian government does not notify the Department of State when it detains dual nationals," according to the official. "We generally learn about these cases through the detainees’ family or friends. Once we learned about this case, through the Swiss we asked for a stay of execution and expressed our deep concerns about the apparent lack of due process in this case."

Update 2:42 P.M.: State Department Spokesman Mark Toner faced several questions from reporters about Samiei’s reported execution following the Free Beacon’s initial report.

Toner told reporters at the State Department’s daily briefing that the Obama administration had been working through the Swiss to obtain a stay of execution, but that the Iranians never responded.

Administration official petitioned the Swiss to obtain more information from Iran "in order to find out a bit more about who this individual was and more about the case against him. We’re still waiting for that information," said Toner.

Iran never notified that United States of Samiei’s imprisonment, Toner said.

"We don’t have any idea when he was arrested or how long he was held," he said.

When asked if this incident raises concerns about Iran’s willingness to work with the United States following the nuclear accord, Toner dismissed this as "a completely unrelated issue."

At least two other Americans have been arrested by Iran in recent weeks and four others remain in longstanding custody without any change in their status.

"We continues to raise at every opportunity the cases of" other Americans detained in Iran, Toner said. "I wouldn’t necessarily say we deal with Iran from a position of trust. That said, we’re not going to stop raising the cases of these Americans."