Former Chicago Bulls general manager Jerry Krause passed away on Tuesday, according to The Chicago Tribune’s K.C. Johnson. He was 77 years old and battled persistent health issues, including osteomyelitis.

Krause was the general manager during Chicago’s six NBA championship runs in an eight-year span during the Michael Jordan-Phil Jackson era. He was a two-time recipient of the NBA Executive of the Year award. Chicago made the playoffs every season for 13 years under Krause before the franchise began rebuilding in 1998.

“He's relentless,” Bulls owner Jerry Reinsdorf said in 2016 according to The Chicago Tribune. “He works very hard. He comes before the games. He wants to see what players do during batting practice or warmup drills. He seeks out information, talks to a lot of people. And then he keeps everything to himself.”

Krause took over as Bulls GM for Rod Thorn in 1985 one year after the franchise drafted Jordan. He retired from his position in 2003. He is a Naismith Basketball Hall of Fame finalist in the contributor category, according to Johnson.

There's a side of Krause that not many people got to see and came out more fully as he aged. He loved the city of Chicago immensely. — K.C. Johnson (@KCJHoop) March 21, 2017