Alex hired Duello and Zeref to protect a dark black gemstone while it was transported to a buyer outside the city. At which point a pair of bounty hunters attacked them and took not only the stone but all of their money and weapons.
Alex and a few of his friends were in the Monarch and Butterfly, drinking the loss away when Duello and Zeref entered the inn. They attacked the party in a drunken rage.
He was killed during the battle along with all of his friends.
There are hints that he was working for some other power. A letter that Duello found on his body proclaiming Alex as a dead man for having lost the stone.