A San Diego man has pleaded guilty to lying during a terrorism investigation of his brother, who was killed while fighting for the Islamic State in Syria.

Marchello McCain acknowledged in a plea agreement Monday that he supplied the FBI with false information about his brother's jihadist plans and how his brother's trip overseas trip was financed.

That carries a potential eight-year federal prison sentence.

Thirty-three-year-old Douglas McCain was reported killed in 2014 while fighting the troops of Syrian President Bashar Assad. He's believed to be the first American jihadist to die while fighting for the Islamic State in Syria.

McCain had denied knowing that his brother planned to fight for the terrorist group. In his plea agreement, he admits paying for his brother's airline ticket to Turkey.