The Saints gave the D-line coach a three-year contract and the title of assistant head coach, Rittenberg adds. Tight ends coach Dan Campbell previously held the assistant head coach role before reportedly leaving New Orleans to become the Detroit Lions' head coach.
Nielsen will stay in the Big Easy after being with the Saints for the past four seasons. The USC alum has spent time coaching at his alma mater, as well as Idaho, Ole Miss, and NC State.
Nielsen was the leading candidate to become LSU's next defensive coordinator. He even informed New Orleans head coach Sean Payton that he intended to accept the position Monday, per Jane Slater of the NFL Network.
The Tigers moved on from their previous defensive coordinator, Bo Pelini, at the end of the 2020 season. LSU allowed 492 yards and 34.9 points per game in the last campaign, and it gave up at least 600 yards in four contests.