Adam Johnson played college hockey for University of Minnesota Duluth, which played in the 2017 Frozen Four because of an overtime game-winning goal he scored in the region final. (Nam Y. Huh/The Associated Press)

Police in England are citing investigative complexities as their criminal inquiry stretches past six months into the on-ice death last fall of a Minnesota hockey player whose neck was slashed by an opponent’s skate during a professional game.

Hibbing High School star Adam Johnson, 29, was playing for the Nottingham Panthers on Oct. 28. He was carrying the puck into the offensive zone when Sheffield Steelers defenseman Matt Petgrave’s skate blade slashed below his helmet. Johnson died at the hospital from the gash to his neck.

A little more than two weeks later, police arrested Petgrave on suspicion of manslaughter. He was soon released on bail as the inquiry continued, and his bail was renewed Tuesday until June 26.

“Adam’s loved ones remain at the forefront of our minds as this complex investigation continues,” police said in a statement that announced the bail extension but offered no other information about the case.

“If there are any developments before the new bail expiry date,” the statement continued, “these will be issued proactively on the South Yorkshire Police website.”

After graduating from Hibbing High, Johnson played two years with the University of Minnesota Duluth Bulldogs and 13 games with the NHL’s Pittsburgh Penguins before heading to Europe and eventually joining the Nottingham Panthers of the U.K’s Elite Hockey League.

One of Johnson’s Nottingham teammates who was on the ice when the injury occurred spoke out this week and cautioned people to not judge Petgrave’s actions prematurely.

“The people that were on the ice, and the people in the stands, they know no one wants to do something like this,” Victor Bjorkung said in an interview with BBC Sport.

“It’s such a freak accident, and it is so fast,” Bjorkung continued. “You can watch the video and you can zoom in and you can slow it down and do all these things. It’s so easy to sit in the stands and think, ‘He did that, he did this.’ But if you watch it in real time, you know it’s too fast to judge.”

Bjorkung, who played junior hockey in Fargo and Sioux Falls before skating with Ohio State University for two seasons, said he remembers most of when Johnson was injured and the immediate aftermath.

“It still feels unreal,” said the defenseman from Sweden, who is now playing professionally in Slovakia. “I do get a lot of flashbacks, and they’re not very pleasant.”