‘But an iron bullet isn’t conclusive, is it?’

‘Iron is made strong by the addition of various impurities. Pure iron is very soft, whereas iron with the right mix of impurities becomes steel. So I had the iron content analyzed. The proportion of iron, carbon and other impurities.’

‘Okay, I get iron, Hans, but what does it tell us?’

‘Well, guess what I found? An exact chemical match. Not only are these bullets of a similar type, they are from the same batch.’

‘Is that admissible?’

‘Who knows what the DA would accept, but for a detective, knowing there is a real link is worth something in its own right. Correct?’

Harper’s skin was tingling. Hans was a showman all right. This was the first piece of real physical evidence, providing a link between the three murders.

‘The bullets might not be from the same gun, but they were manufactured in the same factory, at the same time, is that right?’ said Denise.

‘Yes.’

Harper caught Denise’s thinking. ‘A munitions factory must make a million bullets of the same type at the same time. How does this give us a link?’

‘It’s not absolutely conclusive. I never said it was. But who makes iron bullets, these days? And iron is different from lead. This match is not close, it’s identical. Same batch. How many killers are there in New York using old iron bullets?’

‘You’d say not many,’ said Harper.

‘One. No more,’ said Hans.

‘Can you tell me anything more about these bullets?’ said Harper.

‘I have to continue my work. At the moment, I don’t know what they are or where they were made. I will try for you, Detective.’

Harper stood up and let the idea swim in his mind. It was a material link between the cases. And that meant that he now had evidence linking three Jewish murders. It was potentially explosive.

North Manhattan Homicide

March 10, 8.04 a.m.

Harper’s head was full of iron bullets as he ran up to the investigation room with Denise. She put her arm out, touched his. ‘What do you think it means?’ she asked.

‘Our killer is not new to this game. He’s tried before.’

‘What else?’

‘He’s not politically motivated. He’s killing people because they’re Jewish.’

‘Can we be sure? There’s just three murders.’

‘Each killed in similar ways with iron bullets. He doesn’t want to get caught, does he?’ Tom said. ‘If we’re right, then the man in prison for killing Esther Haeber is the wrong man.’

‘And that adds something vital to our profile. He’s stalking these people, killing them, then setting up other people and staging it to avoid us joining the dots.’

‘Intelligent, strategic, psychotic,’ said Tom.

‘Add brutal and determined. He wants to carry on. He really enjoys this. Like some… necessity, you know.’

‘A religious killer?’ asked Harper.

‘Yeah, that’s what I was thinking. It has that visionary zeal about it.’

‘God help us, then.’

‘Or just avoid helping him, if at all possible.’

Harper left Denise and marched into Captain Lafayette’s office. ‘I got a link for you.’

Lafayette stood up. ‘Really? Evidence?’

‘Yes, real evidence.’

‘Go on, tell me.’ Lafayette moved round the desk. ‘We’re getting busted on this by the hour. They want to know why Lukanov walked. I need some good news.’

Harper produced a printout of Hans Formet’s photographs. ‘We’ve discovered a link between the bullets found at the Capske scene and the Esther Haeber and Marisa Cohen scenes. It links each murder.’

‘What’s the link?’

‘The bullets are all made of iron,’ said Harper.

Lafayette looked at the pictures. ‘What’s the significance of that?’

‘Iron was used to manufacture bullets at some times in the past, but it’s rare. These bullets are very rare, therefore linked, Captain.’

‘Coincidence?’

‘No.’

‘Come on, what you got? Three bullets made of iron, separated by four months, one on a case with a conviction? You know, Harper, even your fans wouldn’t buy this.’

‘It’s a link.’

‘Could it be contamination?’

‘Please, Captain. This is a breakthrough. I nearly choked. There’s some animal on the loose, taking these people out because they’re Jewish. I think we’ve got a serial killer at work.’

‘It’s not a complete picture, Harper.’

‘Complete enough. I need to take these homicides together. We need a task force. I’ll want a liaison with Brooklyn Homicide. We have to reopen the Esther Haeber case.’

Captain Lafayette sat back down and directed one of the fans on his desk towards his face. ‘Are you sure it’s enough? I know you want this, but we’ve got to be sure, Harper.’

‘Captain, I need some authority here. I need to take this forward. You’ve got to trust me on this one.’

‘The iron’s not enough. I need more. Go and check out this guy who got jailed for the Haeber murder.’

‘I’m on my way soon as we’re through here. But you’ve got to understand that the iron matches. There’s an exact chemical fingerprint to iron. These three bullets were from the same batch.’

‘You got anything that matches that bullet to a particular gun?’

‘No, it’s mangled all out of shape. But the chemical properties are identical.’

‘Bullets are made in big batches, Harper. Big, big batches.’

‘But this is not what bullets are made of now. No one uses iron today. These are incredibly old bullets. Possibly antiques.’

Lafayette pushed his chair back and stared up. ‘Okay, Harper. I’ll take your word. We’ll get some help. Run with it. But we got to talk to people about how to handle this. You know what this is.’

‘Of course I do. Some psychopath is killing Jews.’

North Manhattan Homicide

March 10, 11.05 a.m.

Eddie and Denise nodded silently as Harper talked through his visit to see Bruce Lyle, the man imprisoned for the murder of Esther Haeber.

‘So you’ve got nothing to show for your efforts?’

Harper shrugged. ‘He’s not the guy, in my opinion, but we need evidence to get the case re-opened and that means catching the real killer. He says he was framed — that someone planted the rings. I think our killer chose an easy target. They found illegal firearms and cocaine in his place, so he’s got three violations to serve.’

‘But he’s no killer?’

‘No.’

‘What else you got?’ said Eddie.

‘We’ve got something on the note from the kidnapper. It’s got mildew on it, so it was written somewhere damp. But the main thing is the typeface and ink. It’s strange.’

‘How?’

‘They’ve got a pretty full database of typewriters and fonts down there. They tell me this is something unusual.’

‘Just like the bullets.’

‘Right,’ said Harper. ‘They say this is from an antique typewriter. German make, around 1934. They are pretty sure it’s a Torpedo Portable Typewriter. It was designed for military use and only wrote in black. Not red ink.’

‘What the hell does that mean?’ said Eddie.

Denise nodded to herself. ‘This guy is delusional. Aaron noticed the Nazi symbols in the way he kills. Now an antique German typewriter. He’s not a neo-Nazi, Harper. He thinks he is a Nazi, one of the originals.’

‘It’s a very rare model,’ said Harper. ‘Not many people deal in these. We might be able to track something.’

‘Give me the printout,’ said Eddie. ‘I’ll see what I can do.’ He got up and walked towards Gerry Ratten.

Harper’s cell phone rang and broke the somber mood. It was Hans Formet.

‘You need to come round,’ said Hans. ‘You need to come round now.’

‘What for?’

‘I know what your bullets are. I know where they come from. And this is strange.’

‘That’s great, Hans, we’ll be there as soon as we can.’

Within the hour, Harper and Denise were back in Hans Formet’s homemade lab, with a cup of coffee each, listening to the long rambling story of the man’s genius.