Depeche Mode founder Andy Fletcher died of an aortic dissection - a tear in a main artery from his heart.
The keyboardist passed away suddenly aged 60 on 26 May - a death that shocked fans and his bandmates.
In a statement posted on Instagram on Monday, the group revealed the cause of Fletcher's death, and that he hadn't unduly suffered.
"A couple weeks ago we received the result from the medical examiners, which Andy's family asked us to share with you now," their statement read. "Andy suffered an aortic dissection while at home on 26 May. So, even though it was far, far too soon, he passed naturally and without prolonged suffering."
They went on to thank their fans for their support, adding, "It's been a strange, sad, disorienting few weeks for us here, to say the least. But we've seen and felt all of your love and support, and we know that Andy's family has too."
Remaining members Martin Gore and Dave Gahan went on to reveal that a "celebration of Andy's life" took place last week.
"(It) was a beautiful ceremony and gathering with a few tears, but filled with the great memories of who Andy was, stories of all of our times together, and some good laughs," they wrote.
Fletcher formed a precursor to Depeche Mode with Gore and future Erasure star Vince Clarke in the late 1970s, with frontman Dave Gahan joining in 1980. Clarke left the group after the release of their breakthrough album Speak & Spell the following year.