if a player casts Grab the Reins entwined and steals a creature with Murder Investigation attached and sacrifices it, will Murder Investigation trigger?

Can it still reference an illegally enchanted creature and trigger before SBA's remove the aura?

Great question, Todd. Let me add one followup for this: if Murder Investigation does trigger, who gets the Soldiers?

(Note: I'm also locking the thread until an Official source answers our question.)

The controller of Murder Investigation will get tokens.

There's two elements here:
1. Murder Investigation has “Enchant creature you control.” This changes what the Murder Investigation can be attached to. An aura cannot be attached to an object which does not satisfy the description. If the object or the description changes and violate the condition, the aura will be put in the graveyard next time state-based actions are checked.
2. Murder Investigation has a triggered ability that begins with “When enchanted creature dies, …” Here it does not specify anything about enchanted creature, so as long as it's a creature, it will trigger when it dies. There's no mention of a controller, so who controls the creature doesn't matter here.

With these two, we see that with an entwined Grab the Reins the creature changes controllers then is sacrificed before state-based actions are checked, so Murder Investigation will trigger. The controller of Murder Investigation controls its triggered ability. Because Grab the Reins doesn't change who controls the aura, the old controller will get the tokens.

Daniel Kitachewsky
L3, Paris, France
Rules NetRep