Slugger Greg Halman, 24, was found bleeding from a deep stab wound in the early hours of Monday morning in his family's home in Rotterdam, Holland, as we reported here.
His 22-year-old brother Jason, was busted at the scene, where ambulance paramedics were unable to revive Halman, who broke into the Seattle side last year.
Rotterdam Police spokeswoman Patricia Wessels said: "From what we have learned so far there was an argument between the two brothers over loud music being played."
In the meantime tributes have been pouring in for the well liked dutch international.
MLB commissioner Bud Selig said in a statement: "The loss of a talented 24-year-old young man like Greg, amid such tragic circumstances, is painful for all of us throughout the game.
"On behalf of Major League Baseball, I send my deepest condolences to the entire Mariners organization and to all those whose lives were touched by Greg."
Mariners chairman Howard Lincoln, president Chuck Armstrong and general manager Jack Zduriencik paid tribute to Halman on behalf of the club.
They said in a statement: "Greg was a part of our organization since he was 16 and we saw him grow into a passionate young man and talented baseball player.
"He had an infectious smile that would greet you in the clubhouse, and he was a tremendous teammate. Our thoughts and prayers go out to Greg's family."