There was a reason the killer hid the key under the lamp. She just had to figure out why.
The five lights, which were on articulated arms, were reminiscent of medusa’s hair from Clash of the Titans, and were fixed atop a tall, narrow pole. The base of the lamp was matte grey.
The underside of the base was black, but coated with a sticky substance that had tentatively been identified as blood. The bronze key had been taped to the underside and was stained red. She would have to check, but she was fairly sure it opened the basement.