The FBI has admitted that it was aware of alleged threats of violence made last year by the 14-year-old suspect arrested in the shooting at Apalachee High School in Georgia in which four people were killed and nine others wounded. At the time, the agency passed the information on to local law enforcement. Jackson County Sheriff Janis Mangum, whose deputies first questioned the shooter's family in 2023, spoke to CBS News' Mark Strassmann Thursday. For decades, the epidemic of school shootings seems to be something the U.S. has been unable to change. Apalachee High School in Winder, Georgia, became the site of the latest such tragedy, where four people were killed Wednesday. Jim Axelrod examines how school shootings seem to be a problem with no solution. Former President Donald Trump pleaded not guilty Thursday to revised federal charges related to his alleged efforts to overturn the results of the 2020 election. The revised charges stem from a Supreme Court ruling in July that gives presidents immunity from prosecution for what are deemed to be official acts. For decades, the epidemic of school shootings seems to be something the U.S. has been unable to change. Apalachee High School in Winder, Georgia, became the site of the latest such tragedy, where four people were killed Wednesday. Jim Axelrod examines how school shootings seem to be a problem with no solution. Two students and two teachers were killed when a 14-year-old student opened fire in Apalachee High School in Georgia Tuesday. They were identified as Richard Aspinwall, Christina Irimie, Mason Schermerhorn and Christian Angulo. Jericka Duncan has more on who they were.