They met at the house and went to the door, James let himself in and tried a light switch, no light. He tried all the switches that he could find, finally finding a working light switch down the hall.
On his way back to the door where his friend was waiting he tripped and fell to the floor, his friend came running up to help him and realized that he had just tripped over the body of James' girlfriend.
The police were called and made an arrest the same day.
Who did they arrest and why?