Sense Sonnet - Chiller

Double Death

I became nanny to twin boys.
At the time they were six years old.
One day they were playing with toys
When a tragedy did unfold.
One fell down steps and hit his head.
He lay motionless on the floor.
I felt his pulse and he was dead.
The other twin ran out the door.
Soon thereafter I heard him scream.
Upon the floor he too did lay.
And he was dead - was this a dream?
The police came later that day.

And now I sit in a jail cell.
What did happen - I cannot tell.