Couric on Lauer: "This was not the Matt we knew"

Katie Couric and Matt Lauer.
Katie Couric and Matt Lauer at the 2014 UNICEF Snowflake Ball. Photo: Stephen Lovekin / Getty Images for UNICEF

Katie Couric, 61, in a PEOPLE exclusive, breaks her silence about the firing of Matt Lauer, her co-host on "Today" for 15 years: