Marino was not very familiar with drownings, since people rarely committed murder that way, so he was intensely curious. He wanted to understand everything I was doing.

"Actually, there are a lot of things I'm doing," I said as I worked. "I've already made a skin pocket on the side of the chest, filled it with water and inserted a blade in the thorax to check for bubbles. I'm going to fill the pericardial sac with water and insert a needle into the heart, again to see if any bubbles form. And I'll check the brain for petechial hemorrhages, and look at the soft tissue of the mediastinum for extraalveolar air."

"What will all that show?" he asked.

"Possibly pneumothorax or air embolism, which can occur in less than fifteen feet of water if the diver is breathing inadequately. The problem is that excessive pressure in the lungs can result in small tears of the alveolar walls, causing hemorrhages and air leaks into one or both pleural cavities."

"And I'm assuming that could kill you," he said.

"Yes," I said. "That most certainly could."

"What about when you come up and go down too fast?"

He had moved to the other side of the table so he could watch.

"Pressure changes, or barotraurna, associated with descent or ascent aren't very likely in the depth he was diving.

And as you can see, his tissues aren't spongy as I would expect them to be were he a death by barotraurna. Would you like some protective clothing?"

"So I can look like I work for Terminex?" Marino looked in Roche's direction.

"Just hope you don't get AIDS," Roche wanly said from far away.

Marino put on apron and gloves as I began explaining the pertinent negatives I needed to look for in order to also rule out a death by decompression or the bends, or drowning. It was when I inserted an eighteen-gauge needle into the trachea to obtain a sample of air for cyanide testing that Roche decided to leave. He rapidly walked across the room, paper rattling as he collected his evidence bag from a counter, "so we won't know anything until you do tests," he said from the doorway.