Mark Matter and his plane.(Courtesy of Dave Cannon)Last December, Mark and Cecilia Matter lost their lives when their red plane crashed into Marvel Dome, a snow-covered mountain near the family’s mine. Authorities now consider the Aniak couple’s death to be a suicide.Listen nowAccording to a report released by the National Transportation Safety Board (NTSB), authorities couldn’t find any mechanical issues with the Matters’ plane that could have caused the accident. The report concludes that Mark Matter must have crashed the plane intentionally.“Unfortunately, there are no winners in this one,” NTSB spokesperson Clint Johnson said. “Our hearts go out to the family.”Johnson added that the NTSB worked closely with the State Troopers on this case, following the lead of their investigation. According to the Alaska Dispatch News, friends and family told the Troopers that Cecilia Matter was sick with cancer at the time of the crash. In a past interview with KYUK, the Matters’ children said that their mother didn’t have long to live.Johnson said that in his experience, suicides by plane are rare.“In my 20 years there have been roughly three,” Johnson said. “We’ve always had suspicions, maybe, but the ones we were able to rule are suicide are very, very very few.”The Matters’ children declined requests for further comment. In a previous interview, they told KYUK that their parents were inseparable.