In a brief statement, the FBI wrote on its website that the three men "were on the grounds of the U.S. Special Mission when it was attacked."
"These individuals may be able to provide information to help the investigation," the FBI said.
Today White House spokesperson Jay Carney maintained that it has been "the focus of the President and his teams to both investigate... what happened in Benghazi and why and to take action to ensure it doesn't happen again, and to investigate the act itself and to bring to justice those responsible."
Still, more than seven months since the attack, U.S. authorities have not taken any suspects into custody.
In addition to Ambassador Stevens, State Department computer specialist Sean Smith and former Navy SEALs Glen Doherty and Tyrone Woods were killed in the attack.
Carney also denied allegations that any government agency was "blocking" whistleblowers who wanted to testify before Congress about Benghazi, echoing comments made by President Obama and State Department spokesperson Patrick Ventrell Tuesday.
Victoria Toensing, a lawyer for one of the State Department employees who she said witnessed the attack and is seeking to share the story fully with Congressional investigators, said the department is not being entirely truthful. Toensing maintains that asking employees, who are acting as whistleblowers, to come forward, identify themselves and then inform the State Department that they are seeking council before they have representation leaves them vulnerable to intimidation and retribution.
"These people want their own lawyers," Toensing told ABC News Tuesday. "They shouldn't have to go in to their employer what I call 'naked', without an attorney."
Today the State Department said in a letter to a Republican lawmaker that private attorneys can contact the State Department on their clients behalf, and no such requests have been made related to Benghazi.
Republicans lawmakers said they intend to call the unnamed whistleblowers before the House Oversight Committee next week.
Saying the attack happened "a long time ago," Carney accused the GOP of continuing to make political hay of the deadly event.
"The politicization of this issue is unfortunate and it continues unabated," Carney said.
The FBI is asking anyone with information on the three men in question to contact the bureau at BenghaziTips@ic.fbi.gov.