What killed her?

[freemare]

So this morning I go out to the coop and open up the door, everything seemed fine. Girls where in their nesting boxes laying some eggs...till I looked down. One of my silver laced red wyandote hens that i hatched last year, that just started to lay was dead on the ground. No feathers out of place. She had her feet tucked under her and her head was lowered to the ground. What happened? could chickens dye of a heart attack? here is a pick of the girls. She was fine the day before, no evidence of any attack.

 

[sourland]

Two frequent causes of sudden death in chickens are heart attack and fatty liver disease.