An al Qaeda terrorist stated in a recent online posting that U.S. Ambassador to Libya J. Christopher Stevens was killed by lethal injection after plans to kidnap him during the Sept. 11 attacks in Benghazi went bad.

The veracity of the claim by Abdallah Dhu-al-Bajadin, who was identified by U.S. officials as a weapons expert for al Qaeda, could not be determined. However, U.S. officials have not dismissed the terrorist’s assertion.

An FBI spokeswoman indicated that the bureau is aware of the claim but declined to comment because of the ongoing investigation into the Benghazi attacks.

“While there is a great deal of information in the media and on the Internet about the attack in Benghazi, the FBI is not in a position at this time to comment on anything specific with regard to the investigation,” spokeswoman Kathy Wright said.

A State Department spokesman had no comment.

The FBI is investigating the deaths of Stevens, State Department information officer Sean Smith, and former Navy SEALs Tyrone Woods and Glen Doherty. They were killed in attacks that U.S. officials say were carried out by an al Qaeda-linked group known as Ansar al-Sharia.

A State Department Accountability Review Board report and an interim House Republican report on the attacks gave no cause of death for Stevens, whose body was recovered by Libyans in the early hours of Sept. 12.

The House report, “Interim Progress Report for the House Republican Conference,” said that “Libyan doctors tried unsuccessfully to resuscitate Ambassador Stevens upon his arrival at the hospital.”

To date, no official cause of death for Stevens has been made public, although it was reported that a Libyan doctor who examined Stevens said he died from apparent smoke inhalation and related asphyxiation.

Video and photos of Stevens being handled by a mob in Benghazi were posted on the Internet. It is not clear from the images whether he was dead or alive at the time.

According to a March 14 posting on an al Qaeda-linked website, Dhu-al-Bajadin stated that Stevens was given a lethal injection that was overlooked during the autopsy.

The “plan was based on abduction and exchange of high-level prisoners,” the terrorist wrote on the prominent jihadist Web forum Ansar al-Mujahideen Network. “However, the operation took another turn, for a reason God only knows, when one of the members of the jihadist cell improvised and followed Plan B.”

Dhu-al-Bajadin’s claim of assassination also was copied to the Ansar al-Mujahidin website from the al Qaeda-accredited website Shumukh al-Islam. That site is open only to members, and the claim initially was posted for Dhu-al-Bajadin by a member identified as Adnan Shukri.

The reference to Shumukh al-Islam has boosted the credibility of the claim among some U.S. intelligence analysts. A Western intelligence official said Dhu-al-Bajadin is a well-known jihadist and a key figure behind a magazine called Al Qaeda Airlines.

According to this official, intelligence analysts believe Dhu-al-Bajadin’s claim of assassination by lethal injection appears aimed, in part, at pressuring the U.S. government on its handling of the Benghazi attacks.

The article did not say what substance was used in the lethal injection. It also stated that the State Department had come under criticism for not providing adequate security in Benghazi before the attacks.

Dhu-al-Bajadin said he had more details about the attacks and the assassination, but would not reveal them in the posting.

The Washington Free Beacon obtained a copy of the translation of Dhu-al-Bajadin’s posting in Arabic.

The article stated that lethal injections are done in “more than one place in the human body that autopsy doctors ignore when they see that the symptoms are similar to another specific and common illness.”

“Anyone who studied the art of silent assassination that spies applied during the Cold War would easily identify these parts of the body,” the article stated.

Dhu-al-Bajadin has said the Al Qaeda Airlines publication is not solely focused on aviation but was chosen as a way to instill fear in the enemy.

• Bill Gertz is the senior editor of the Washington Free Beacon.