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

Marchello McCain, 34, acknowledged in a plea agreement that he supplied the FBI with false information about his brother’s plans to be a jihadist in Syria and the financing for his brother’s overseas trip, federal prosecutors said.

McCain faces up to eight years in federal prison when he is sentenced in December.

“Lying during a terrorism investigation is a very serious crime because the security of our nation and citizens is at stake,” U.S. Attorney Laura Duffy said in a statement. “This case is particularly important because it involves … a brutal foreign terrorist organization that threatens to induce our youth into committing violence against foreigners and U.S. citizens alike.”

McCain’s brother, Douglas McCain, 33, was reportedly killed in 2014 while fighting with the Islamic State, the extremist group trying to overthrow the government of President Bashar Assad. He was believed to be the first American jihadist with the group to die there.

The San Diego man traveled to Syria to follow his basketball buddy from Minneapolis into the terrorism fight.

Marchello McCain pleaded guilty to making false statements involving international terrorism. He had denied knowing that his brother planned to fight for the terrorist group and told the FBI that he thought his brother was going to Turkey to play music and teach English.

In his plea agreement, McCain acknowledged that he allowed his brother to use a debit/credit card belonging to McCain’s wife to buy airline tickets to Turkey and put money to cover the purchase into his wife’s account.

McCain’s brother left the United States in March 2014 and five months later was reported killed fighting against the Free Syrian Army.

In 2005, Marchello McCain was convicted of shooting at two people in Minnesota. This January, he pleaded guilty to six counts of being a felon in possession of guns, ammunition and body armor.

In that plea agreement, McCain acknowledged that about three weeks before his brother departed, the two went to a San Diego gun range and shot weapons that included a semi-automatic-style rifle and a shotgun, federal prosecutors said.