“How do you know that?” asked Mangeshkar. “How can you be sure he didn’t simply suffer a traumatic episode due to the weakness of his heart? Why does it have to be linked to his bruises?”

“The marks go deep, Meera; they were made with great force. The one on his chest has actually torn several layers of the epidermis. They weren’t caused by just bumping into the furniture, and they’re fresh enough to have occurred at his time of death. There’s a secondary contusion on his skull where he glanced against the table edge as he fell. His right shoe twisted, causing a faint spiral pattern on the flooring, and he instinctively put out his left hand to break the fall, so he still had consciousness at that point. Dan lifted a partial palm print from the floor.

“No instruments of any kind have been removed from the wall cases, and there are no prints on the blades of the broken fan, even though I had my money on it having been used as a weapon. It couldn’t have simply spun down, striking him twice in succession. It’s not a boomerang. But as a weapon it would have carried prints easily, so I was surprised that none showed up. However, when I examined the clean edges of one of the blades, I found a tiny sweat mark that suggests it might have come into contact with Finch’s neck.”

“If you’re telling us that someone else was there-leaving aside that impossibility for a moment-and chose to hit him with a ceiling fan, surely you can run a DNA match on his sweat marks, and separate them out from any other prints in the room?” asked Banbury, whose love of technical wizardry made him want to press the human genome into service in the form of computer code.

“Dan, we have Finch’s prints on file, and I promise you, there are no outsider prints at all. I dusted the place from top to bottom, and all we have are finger marks from other members of the PCU. I know that because you’re all on file. So, our time line.” He produced a piece of chalk and began scratching away on the board, oblivious to the teeth-gritting noise it made. “Finch arrived for work this morning at eight A.M. There was nothing booked on his schedule for the day, so it’s hard to be totally accurate what he got up to. Dan, you checked the phone log.”

“No outgoings in that time, and the internals don’t register, but we know he called Land to talk about his position here at the unit, because Land called Mr. Bryant to discuss the matter further.”

“Then Sergeant Renfield came over from Albany Street station with a docket for the body that was delivered to the Bayham Street Morgue.”

“Finch had a case?”

“He’d agreed to help Renfield out. Young unidentified female, probably living rough on the streets of Camden, found dead in a doorway of the Office shoe shop this morning, corner of Inverness Street and Camden High Street, exposure combined with a drug intake. Colin, you rang around the hostels, didn’t you?”

“No obvious candidates yet, Sarge. I’m waiting for the Eversholt Street Women’s Refuge to call me back.”

“Did Oswald carry out an autopsy on her?” asked Meera.

“He’s supposed to wait for hospital notes,” said Banbury, “but he’d started some preliminary exploration, then locked her back in the body drawer. I just took a quick look at her, and now the cadaver can’t be moved anyway, at least until Giles and I have finished in there. No-one’s come forward to claim her, and I don’t suppose they will straightaway.”

“Did Oswald leave any notes?”

“Just an estimated time of death on the report form, which he set at five-thirty A.M., an external description and some basic observations about her condition.”

“No other appointments or personal notes to himself?”

“Nothing that I can find,” said Banbury. “There’s no obvious point of entry for an intruder, and no way of gaining access. Giles, you checked Finch’s body for long-term defects, didn’t you?”

“He shows some symptoms of having had a weak heart,” said Kershaw. “I took a look at an artery and found it pretty furred up. I don’t suppose he’d have lasted very long in retirement, but I don’t think he killed himself. There’s a two-centimetre cut on the palm of his left hand, fresh and very fine. It looks like it was made with the point of a scalpel. He’d put a new blade in this morning and dropped the wrapper in his bin. I have to say that the position of his body suggests an attack. What if he was surprised, raised his hand in defence, was jabbed, and the attacker struck again with the handle? Of course, that raises more questions than it answers. Anyway, here’s your time line.” He tapped the blackboard with his chalk.

“Finch enters the morgue at eight A.M. and locks the door on the inside, returning the key to its hook. He gets an immediate call from Renfield saying that he’s on the way over with a case. Renfield turns up ten minutes later with someone, presumably a paramedic, drops off the body and they leave. Finch starts work, then stops when he realises he won’t get the hospital notes until later in the day-there’s a bit of confusion about this at the moment-so he locks the corpse in one of the drawers and starts to write up his notes. We know that at around eight-thirty A.M. he calls Land and tries to get him to rescind his resignation. Apparently he began to have doubts about leaving after talking to Mr. Bryant yesterday. At nine forty-five a.m. I go to see him about his refusal to recommend me for the position of unit pathologist, and I admit it, we have a bit of a contretemps. While we’re arguing, Meera turns up, wanting to sit in on the rest of the autopsy.”

“It couldn’t have been very comfortable for you,” said Longbright, “having to confront the man who had just destroyed your chances of promotion.”

“I don’t much care for your implication,” Kershaw said, bridling. “I’ll admit I wasn’t comfortable about seeing him, but I’m a professional. I didn’t let my true feelings show.”

“How long did you stay?”

“Only a few minutes. Oswald told me he was waiting for documentation to come through before continuing his casework, so I left him to it. I don’t think he’s legally bound to wait for it, but that’s what he told me.”

“We know he was in an argumentative mood. Did he seem different in any other way?”

“It’s hard to remember.” Kershaw seemed so uncomfortable with the question that Longbright had the distinct impression he was holding something back.

“And to your knowledge he had no further visitors.”

“No, but we have no way of being sure because no-one has to get signed in at Bayham Street. You can walk in from outside without being seen so long as you have the access code to the front door. The morgue is cold, and his body temperature may have fallen sharply, I say may because the thermostat’s on the fritz and I can’t tell if the heaters were on the whole time, but I assume he died between ten A.M. and eleven A.M.”

“By which time it was already snowing hard,” Longbright added, making a note.

“Yes, that’s an odd thing,” Kershaw admitted. “The morgue lights were off, and given the size of the windows it means that Finch must have been sitting in virtual darkness, which means that his killer-if a killer it was-attacked without needing much light. There’s a street lamp outside, but the bulb is broken. And as I say, the key to the morgue door was still hanging on the hook.”

“I don’t suppose we have a way of checking how many other keys were still in place at any time through the day.”

“I know they were there before, because I had to borrow one, and the remaining keys were all there when I returned mine an hour later.”

“There must be absolute secrecy about this while we conduct an internal investigation,” Longbright warned. “If that Home Office hit man Kasavian finds out what’s happened here, we’re dead.”

“We won’t be able to let John and Uncle Arthur know yet,” said April. “They’re only contactable on their mobiles until they get to their hotel, and the lines of communication won’t be secure.”