2015 Cotton Bowl: Michigan State vs. Alabama - Dec. 31, 2015

Michigan State defensive lineman Damon Knox (93) tackles Alabama running back Derrick Henry (2) in the first quarter of their 2015 Cotton Bowl game at AT&T Stadium in Arlington, Thursday, December 31, 2015.

(Mike Mulholland | MLive.com)

Michigan State's defensive line keeps getting thinner.

Veteran defensive tackle Damon Knox will not play for the Spartans in 2016 and has decided instead to pursue a career in law enforcement, the school announced on Friday afternoon.

The Muskegon native participated in spring practices in preparation for the season after graduating in December.

Spartans coach Mark Dantonio said earlier this year that the school would seek a waiver for a sixth year of eligibility for Knox, but a school spokesperson said on Friday the school did not file paperwork with the NCAA for that waiver.

"Damon has been a major contributor to our success the past five years," Dantonio said in a statement. "We appreciate his time and commitment to the Michigan State football program and wish him the best in his future endeavors."

Knox made one start at defensive tackle last year, filling in for the injured Joel Heath. In three seasons, he appeared in 38 games and made 42 tackles, with three starts.

He had drawn praise from Spartans coaches during spring practices for the leadership role he had taken with younger players, and was listed as a starter on the team's spring depth chart.

"We call him coach Knox by trade," Michigan State defensive line coach Ron Burton said last month. "He's been great in the room, he's been great on the field, and we want that continued in the fall."

Knox is the third offseason departure of a defensive lineman for Michigan State. Defensive linemen Montez Sweat and Craig Evans left the team in mid-April, the school announced.

Michigan State was already replacing three defensive line starters from last year.

Redshirt freshman Raequan Williams was listed immediately behind Knox on the Spartans' depth chart. The Spartans are also bringing in four defensive linemen in its 2016 recruiting class.

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