Puzzle of Suspects

The figure in black parked and walked about six blocks to the decaying house, a ghostly presence of time past, its porch half detached from the main house; and the white paint, now shades of gray, appeared to be scratched bare here and there by wind and rain. Walking carefully across the rickety porch, looking in all direction, the dark night figure entered the front entrance, walked down a long hallway, and found the body where it had been placed the night before. After carefully removing boards from the washroom floor, the body slipped easily into the hole; and he poured the sack of lime on it, nailed back the boards, and crept back into the night.