"The Dallas Stars expect all of our employees to act with integrity and exhibit professional behavior while working for and representing our organization," Stars general manager Jim Nill said in a statement. "This decision was made due to unprofessional conduct inconsistent with the core values and beliefs of the Dallas Stars and the National Hockey League."
Nill said during a press conference Tuesday that he was made aware of "a material act of unprofessionalism" over the weekend, and the incident occurred last week. He added that it didn't involve any past or present players, other Stars employees, or a criminal investigation.
Montgomery's dismissal comes one day after NHL commissioner Gary Bettman announced the league's implementation of a zero-tolerance policy of incidents involving league personnel that are "clearly inappropriate, unlawful, or demonstratively abusive." However, Montgomery's departure is not related to that plan, Nill said.
Dallas holds the first wild-card position in the Western Conference with a 17-11-3 record. The club lost eight of its first nine contests to start the campaign but made a drastic turnaround since.
Montgomery was hired prior to the 2018-19 season after an impressive run as the head coach at the University of Denver. The 50-year-old led the Stars to a 93-point regular season and the second round of the playoffs in his first campaign at the helm and had two years remaining on his contract, according to TSN's Pierre LeBrun.
He's the third head coach to be fired this season, following Mike Babcock and John Hynes. Bill Peters also resigned from his position with the Calgary Flames in late November.