Simon has been charged with involuntary manslaughter in his native Dominican Republic. No trial date has been set.
He had to be activated by Sunday from the restricted list, but the Orioles made the move early after playing a 15-inning game on Wednesday and losing 17-5 to the Nationals on Friday night.
Simon will work out of the bullpen. He was 4-2 with 17 saves and a 4.93 ERA in 49 games for the Orioles last season.