A short time before his death, Ambassador Chris Stevens warned a retired senior American military officer against traveling to Libya due to security concerns, the officer told ABC News.

The officer said he had planned to go on a business trip to Tripoli in early October and, in late August, had asked through official channels if it was safe.

Through a diplomatic attache, Stevens said he didn't think it was a good idea because of the "potential of increased risk to foreigners as militias and clans jockeyed for position" as the country rebuilds itself from a civil war that deposed dictator Moammar Gadhafi and left the nation awash in weapons. Stevens' advice was heeded and the trip was canceled.

Stevens was killed along with State Department computer expert Sean Smith and former U.S. Navy SEALs Glen Doherty and Tyrone Woods in a brazen attack on a U.S. diplomatic mission in the eastern Libyan city of Benghazi on Sept. 11.

READ: Four Americans Slain in Libya 'Come Home'

Following the attack, questions arose about the security of the diplomatic mission in such a turbulent country and today Republicans in the House Committee on Oversight and Government Reform sent a letter to Secretary of State Hillary Clinton alleging U.S. officials in Libya had made "repeated requests" for increased security in Benghazi, only to be denied by Washington.

In a response letter, Clinton said an Accountability Review Board (ARB) had been set up to determine "whether our security systems and procedures in Benghazi were adequate, whether those systems and procedures were properly implemented, and any lessons that may be relevant to our work around the world."

"I… would encourage you to withhold any final conclusions about the Benghazi attack until the committee can review the ARB's findings," she wrote.

READ: American Killed in Libya Was on Intel Mission to Track Weapons

The Obama administration has also come under fire from Republicans for initially saying the assault was the result of a protest that was "hijacked" by violent actors, rather than a full-on "terrorist attack," as White House spokesperson Jay Carney called it a week later.

Meanwhile, the New York Times reported today that special operations forces and the CIA are in the process of gathering information on suspects believed to be involved in the attack for kill or capture missions in the event they get the order from the White House. President Obama has said repeatedly that those responsible will "brought to justice."

ABC News' Lee Ferran and Dana Hughes contributed to this report.