Three Days Grace have revealed more details about frontman Adam Gontier's departure from the group. As we previously reported, they have recruited My Darkest Days' Matt Walst to handle vocals on their upcoming tour.

When that was announced the band made a brief statement about the change but now they are telling fans more of their side of the story. They posted the following message on theirFacebook:

"It had been our desire to keep an internal band matter just that, internal. However, after public statements by Adam we feel the need to give our fans the facts. Here's the exact timeline of events over the past few weeks.

"On December 21, 2012, Neil and Brad (via email), our manager and business manager (via federal express) received a letter from Adam's lawyer stating, "Please be advised effective immediately Adam is terminating his involvement with the band Three Days Grace. Adam has been wrestling with a health issue, outlined in the attached letter (a doctor's letter dated December 14), which would have precluded him from touring with the band in 2013 and he wants the group to continue moving forward as they see fit while not holding them back."

"As you can imagine, this came as a complete shock to us. We had just played a series of shows in Hartford and Peterborough the preceding week with no mention from Adam of any health issues or that this resignation letter was coming. We had no idea then that the December 15th Hartford show (which we played one day after the date of the doctor's note attached to Adam's lawyer's letter) would be our final show with Adam as lead singer. Read the rest here.