Jane saw a small man wearing glasses, whom she recognised as one of the passengers in the other Flying Squad car with Stanley. She knew he must be Dabs, as he was wearing latex gloves and carrying a scene of crime case and a camera over his shoulder. He was about five feet six inches tall, early thirties, with dark brown collar-length hair and long sideburns. He was dressed casually in a white shirt, blue jumper, grey trousers and black windcheater.

Jane held out her hand. ‘I’m WDS Jane Tennison. I’ve just started on the Flying Squad today.’

He shook her hand. ‘Pleased to meet you, Sarge. I’m Dave Morgan. DS Stanley mentioned you in the car earlier. We were all a bit surprised as no one knew you were joining the team – especially as you’re a woman.’

‘Well, speaking as a woman, the day’s been quite a surprise for me too,’ she said, forcing a smile and wondering if his ‘woman’ remark was intentionally derogatory.

‘Have you found something?’

She pointed to the two visible cartridge cases and told him there were another two under the car and blood drops on the road.

‘From what a witness told me, the skid mark there is where the Cortina stopped sharply, then a man with a handgun got out and shot at the police car. If he was injured the blood trails might have come from him getting out and returning to the car.’

‘Good spot, Sarge.’ He got a swab out of his pocket and dabbed it in one of the blood spots and the end turned red. ‘And they’re fresh. I’ll take some photos and swabs of the blood . . . From the nearby position of the cartridges to the blood drops I’d say the gun was a semi-automatic. Do you know much about firearms forensics, Sarge?’ he asked politely as he put his case down.

Jane knew a semi-automatic pistol ejected cartridges each time it was fired, but six-chamber Smith & Wesson revolvers, which the Flying Squad used, didn’t.

‘A bit. I’ve dealt with major crimes involving guns, including a shooting murder scene – and post mortems where I assisted the lab liaison sergeant.’

‘Who was the lab sergeant?’

‘Detective Sergeant Paul Lawrence.’

Dabs’s eyebrows raised. ‘He’s a legend when it comes to crime scene examination. I met him at a lecture he did at training school, but sadly never had the privilege of working alongside him.’

He bent down and picked up one of the cartridge cases.

‘Looks like a nine-millimetre Parabellum,’ he observed.

‘What’s a Parabellum?’

‘It’s a type of bullet cartridge and Parabellum is Latin, meaning “prepare for war”, which is appropriate considering what happened here today.’ Dabs showed her the base of the cartridge case. ‘See the markings on the bottom – that’s what we call the head stamp.’