The client came to get the ring while you were gone, and out of boredom, started to score the glass with the ring. By accident, she cut a small hole in the glass and dropped the ring in the shower. The DI took the ring and broke the glass with it. An unrelated woman was shocked by the sound of broken glass and had a heart attack. This woman was the one you saw dead.
You didn't realize it, but the shower was mistakenly set at a drip. The DI took the taps you broke off, turned the water to low flow, and returned the taps you used to maintain the rumor about him being a witch.