A shootout in 1996 was the final straw for Karl Dunbar's wife, a drug bust that turned into a gunfight between Dunbar, other Opelousas police officers and those they were looking to arrest.

While Dunbar wasn't injured, his wife was tired of the constant danger her husband faced as an undercover narcotics officer and demanded he find another job. Dunbar obliged and started coaching the Opelousas High School freshman team that following Monday.

Years later, Dunbar is one of the nation's top defensive line coaches, a respected veteran entering his second season with Alabama after stints with the Minnesota Vikings, New York Jets and Buffalo Bills. Most don't know that Dunbar was once an undercover police officer known as the "Human Battering Ram" because of his ability to break down doors.

The former LSU criminal justice major began working with the Opelousas police department not long after finishing college in 1990, helping the department while also pursuing a professional football career that started with the Pittsburgh Steelers in 1990 and lasted through 1995.

"It was dangerous what he did, but he helped to clean up this city," said former Opelousas police chief Larry Caillier. "He was very instrumental. When he came here and we became friends and he worked undercover, he was very instrumental, and that was the beginning of the end for the drug dealers in the city of Opelousas."

***

Cocaine was a "monster" of a problem in Opelousas back then, according to current police chief Donald Thompson.

Dunbar helped with that, assisting with about 60 drug-related arrests before that 1996 shootout that led to him leaving police work for coaching.

Drug dealers were familiar with Dunbar as a local football star who played at nearby LSU and at the time was in the NFL. Upon his initial contact with the dealer, Dunbar presented himself as a failed football player who had turned to cocaine. Dunbar would then report back to Caillier, sharing information about the dealer and how much cocaine they had to sell. When Dunbar went to meet with the dealer again, he wore a wire, took marked money and had a secret password to indicate to nearby officers when the deal was done. Caillier and others would then bust in and make the arrest.

"He was a great asset for this police department," said Thompson, a detective at the time Dunbar was with the department. "We made a bunch of drug cases because of Karl."

For years, Caillier struggled to catch a particular dealer that he remembers being "super, super evasive."

Police finally got him, largely aided by Dunbar. It was one of Dunbar's first cases, so Caillier was surprised and impressed when Dunbar baited the dealer into making a deal after going to where the man operated.

After making the arrest, as he would often do in those situations, Caillier took the money Dunbar had paid with, pulled out one particular dollar bill and showed it to the dealer.

On there was written, "You got f***ed."

***

In 1991, one of the drug dealers sought revenge. A hit was ordered on Dunbar's life right around the time he was getting married, so a large group of police officers had to attend Dunbar's wedding simply for protection.

That wasn't the last time someone ordered a hit on Dunbar. There were other dealers and other ordered hits, which contributed to Dunbar's wife finally demanding for him to leave the force following the shootout in 1996.

"He put his life on the line, and the department will always be appreciative for what Karl did," Caillier said.

It didn't take Dunbar long to rise up the ranks after transitioning from undercover cop to coach.

After coaching at the high school level for two years, Dunbar got his first college job in 1998 as the defensive line coach at Nicholls State. Two years after that, he linked up with Nick Saban at LSU as a strength and conditioning coach. From there, Dunbar was the defensive line coach at Oklahoma State (2002-03), with the Chicago Bears (2004), at LSU (2005) and then with the Vikings (2006-11), Jets (2012-14) and Bills (2015). He reunited with Saban in Tuscaloosa last May.

Led by Dunbar's defensive line, the Vikings ranked first in the NFL in run defense during each of his first three seasons with the team and second the next year in 2009. Dunbar then helped the Jets improve from 26th in the NFL against the run in 2012 to ranking in the top-five in both 2013 and 2014.

Pass rush production has been there, too. Former NFL star Jared Allen posted 22 sacks under Dunbar's tutelage in 2011 -- tied for second-most in a single season in NFL history and 6 1/2 more than Allen had recorded in any of his first seven NFL seasons.

In his first year at Alabama, Dunbar's defensive line was the strength of a defense that's widely considered one of the best in recent college football history. Two of his defensive linemen, Jonathan Allen and Dalvin Tomlinson, were taken in the first two rounds of the 2017 NFL Draft.

"Coach Dunbar is a great coach, a great defensive line coach," Tomlinson said late last season. "He helps everyone up front, even the outside linebackers, with our pass rush game. He's made us a lot more effective pass rushers. He's one of those coaches who brings stuff to the table you've never seen before - a lot of different pass rush moves, how to read the offensive linemen, how they set. He's made it so that we can read the offensive line a lot better when we pass rush and keying things before the snap, small details that help out a lot."

After the season, Dunbar visited Opelousas and met up with Caillier and Thompson.

Inside Thompson's office, the three traded stories about the lives they led two decades ago. They talked about Alabama football and the defensive line group Dunbar now leads at college football's preeminent program.

They talked about the incredible journey of the man once known as the Human Battering Ram.