Boogaard, an enforcer who signed a four-year, $6.4-million contract on July 1, was found in his apartment, the Minneapolis Star-Tribune reported. The Hennepin County Medical Examiner's office in Minnesota said an autopsy was pending.
"Derek was an extremely kind and caring individual," Rangers president and GM Glen Sather said in a release. "He was a very thoughtful person, who will be dearly missed by all those who knew him. We extend our deepest sympathies to his family, friends and teammates during this difficult time."
The 6-7 Boogaard, 28, sustained several injuries during the season, including a concussion and strained shoulder on Dec. 9 during a fight with Ottawa's Matt Carkner. His head and shoulder hit the ice and Boogaard did not play again.
He underwent treatment for headaches, including acupuncture in Minnesota, and said in March that he was feeling better and skated with the team in practices. He told Newsday at that point that he was looking forward to getting back in shape over the summer and be ready for training camp. But he was sent home before the end of the season.
Boogaard had one goal and one assist and 45 penalty minutes in fourth-line time last season. He injured his hand in a fight early in the season that limited his effectiveness.
Boogaard is survived by his mother, Joanne, and father, Len, his younger brothers, Aaron and Ryan, and younger sister, Krysten.
VIDEO: Frolov and Boogaard Reach Out to Kids