The State Department revealed on Friday that it has discreetly offered a reward of up to $10 million since January for information leading to the those who attacked the U.S. Consulate in Benghazi, Libya on Sept. 11, 2012. The attacked killed U.S. ambassador to Libya Chris Stevens and three other Americans. 

The four men died when militants with possible ties to al Qaeda affiliates attacked the U.S. diplomatic compound, which had lax security, and a nearby CIA annex, Reuters confirms. The attacks ignited acrimonious finger-pointing in Washington. Republicans accused President Barack Obama of shifting his story about who was behind the attacks, and Democrats accused the GOP of using the tragedy to their political advantage. 

The State Department and Secretary of State John Kerry confirmed in a letter to lawmakers on Friday that the U.S. offered the reward as part of the department's "Rewards for Justice" program. Kerry mentioned the reward in a letter to Representative Michael McCaul, a Republican who chairs the House of Representatives Homeland Security Committee. McCaul has previously written to Kerry, asking him why the State Department had not offered a reward. 

"The State Department today confirmed that since January of 2013 the Rewards for Justice (RFJ) program has had a reward offer of up to $10 million for information leading to the arrest or conviction of any individual involved in the September 11-12, 2012 Benghazi attacks," the department said in its statement.

While it is unusual not to publicize rewards, investigators said they have other ways of making sure the information is known "as needed," The Associated Press reports. Investigators have made it known to individuals that there is a cash reward for those who come forward with actionable information concerning the attackers. 

"Due to security issues and sensitivities surrounding the investigation, the event-specific reward offer has not been publicly advertised on the RFJ website," it added, saying the program works without advertising the reward online.