The Hennepin County Medical Examiner announced Boogaard's cause of death Friday, saying it was unclear exactly when the 28-year-old died. Boogaard was found dead in his Minneapolis apartment May 13, five months after he sustained a season-ending concussion with the Rangers.
The medical examiner said no private data on Boogaard would be released, but a statement his family issued through the National Hockey League Players' Association indicated the 6-foot-7 Boogaard had been struggling with pain and addiction.
"After repeated courageous attempts at rehabilitation and with the full support of the New York Rangers, the NHLPA and the NHL, Derek had been showing tremendous improvement but was ultimately unable to beat this opponent," the family said. "While he played and lived with pain for many years, his passion for the game, his teammates, and his community work was unstoppable."
Experts say mixing alcohol and medicines can cause dangerous reactions. Drinking alcohol while taking strong painkillers like oxycodone can result in breathing problems and increase the risk of an overdose, according to the National Institute on Alcohol Abuse and Alcoholism.
The family thanked the Rangers, Minnesota Wild, the NHL and the NHLPA for "supporting Derek's continued efforts in his battle."
"Regardless of the cause, Derek's passing is a tragedy," NHL spokesman Frank Brown said in an email. The Rangers and Wild had no comment.
Boogaard's agent, Ron Salcer, said it's been hard dealing with the death.
"The scary part is Derek was doing so well, so much better," Salcer said, adding that Boogaard was "turning a corner."
Salcer said he feels pain medications have been made too accessible to athletes, who aren't often monitored closely or told about the dangers of what could happen if the drugs are taken the wrong way.
"I do think these pain meds get prescribed way too easily," he said. "Athletes, hockey players, deal with a lot of pain and injuries and want to get through them. There just has to be more education before they get prescribed. That is what concerns me."
He said he hopes other players will learn from the tragedy.
Salcer and a spokeswoman for the Boston University School of Medicine said earlier this week that Boogaard's brain will be examined for signs of a degenerative disease often found in athletes who sustain repeated hits to the head.
Boogaard was known as "The Boogeyman" -- one of the league's most feared fighters. He agreed to a $6.5 million, four-year deal with the Rangers in July and appeared in 22 games last season, finishing with a goal, an assist and 45 penalty minutes.
His final game was Dec. 9 at Ottawa when he fought Matt Carkner and sustained a concussion and shoulder injury. That was the 70th fight of his NHL career, and a replay of it still can be seen on YouTube.
He was out for the last 52 games of the regular season because of his injuries and did not play in the playoffs. He didn't skate again until about three months after the concussion. He was sent home to Minnesota late in the season to work on conditioning.
The 6-foot-7, 265-pound enforcer was drafted by Minnesota in 2001 in the seventh round, No. 202 overall. He played in 255 games with the Wild from 2005 to 2010. He missed four games with the Wild because of a concussion.
Boogaard finished with three goals, 13 assists and 589 penalty minutes in six career NHL seasons.
Born in Saskatoon, Saskatchewan, Boogaard drew notice in 2007 when he and brother Aaron ran a hockey-fighting class. Some voiced concern about such a camp. Boogaard insisted he wasn't teaching kids how to hurt each other, but rather how to protect themselves so they wouldn't get hurt on the ice.
This is the second death of a player in the Rangers organization in the past three years. Alexei Cherepanov, drafted in 2007 but never signed by New York, died at 19 in Chekhov, Russia, in 2008, after collapsing on the bench during a game.
Roman Lyashenko, who briefly played with the Rangers several years ago, was found dead in a hotel in Turkey in 2003. His death was believed to be a suicide.
Earlier this year, Boston University revealed that former enforcer Bob Probert suffered from the degenerative brain disease chronic traumatic encephalopathy (CTE). Probert died of a heart attack last July at age 45. Reggie Fleming, a 1960s enforcer who played before helmets became mandatory, also had CTE.
Wild fans held a memorial service for Boogaard last Sunday at the Xcel Energy Center. Family, friends and former teammates turned out, and remembered Boogaard as a rough-and-tumble guy on the rink, but a gentle giant off the ice. He was noted for his community work and charitable visits to Children's Hospital in St. Paul.
"He exuded this aura about him that made people want to be around him," Wild general manager Chuck Fletcher said Sunday. "He just brought smiles to everyone's faces all the time."
Boogaard's funeral will be held Saturday in Regina, Saskatchewan.
His family said they appreciate the outpouring of love and support they've received.
"It is very comforting for our family to know that, while Derek's life was far too short, he had a great impact on many people who he came into contact with," his family said, adding. "Derek will be greatly missed and will never be forgotten by his fans, friends, and teammates, and especially by us -- his family."