The Laughing Policeman

‘By radio?’

‘Yes. This instruction had already been sent out to the drivers on route 47 by shortly after nine o'clock. On Stockholm Transport's own wavelength.’

‘Go on.’

‘We assumed that there are people who rode part of the way on the bus on this particular run. But so far we haven't traced any such witnesses.’

‘They'll turn up,’ said Hammar.

He pointed to the newspapers and added, ‘After this.’

‘Stenström's watch had stopped at eleven, three and thirty-seven,’ Kollberg went on in a monotone. ‘There is reason to presume that the shots were fired at precisely that time.’

‘The first or the last?’ Hammar asked.

‘The first,’ Martin Beck said.

Turning to the sketch on the wall, he put his right forefinger on the X he had just drawn.

‘We assume that the gunman stood just here,’ he said. ‘In the open space by the exit doors.’

‘On what do you base that assumption?’

‘The trajectories. The position of the fired cartridges in relation to the bodies.’

‘Right. Go on.’

‘We also assume that the murderer fired three bursts. The first forward, from left to right, thereby shooting all those sitting in the front of the bus-marked here on the sketch as numbers one, two, three, eight and nine. Number one stands for the driver and number two for Stenström.’

‘And then?’

‘Then he turned around, probably to the right, and fired the next burst at the four individuals at the rear of the bus, still from left to right, killing numbers five, six and seven. And wounding number four-Schwerin, that is. Schwerin was lying on his back at the rear of the aisle. We take this to mean that he had been sitting on the longitudinal seat on the left side of the bus and that he had time to stand up. He would therefore have been hit last.’

‘And the third burst?’

‘Was fired forward,’ Martin Beck said. ‘This time from right to left.’

‘And the weapon must be a submachine gun?’

‘Yes,’ Kollberg replied. ‘In all probability. If it's the ordinary army type –’

‘One moment,’ Hammar interrupted. ‘How long should this have taken? To shoot forward, swing right around, shoot backward, point the weapon forward again and empty the magazine?’

‘As we still don't know what kind of weapon he used –’ Kollberg began, but Gunvald Larsson cut him off.

‘About ten seconds.’

‘How did he get out of the bus?’ Hammar asked.

Martin Beck nodded to Ek and said, ‘Your department.’

Ek passed his fingers through his silvery hair, cleared his throat and said, ‘The door that was open was the rear entrance door. In all likelihood the murderer left the bus that way. In order to open it he must first move straight forward along the aisle to the driver's seat, then stretch his arm over or past the driver and push a switch.’

He took out his glasses, polished them with his handkerchief and went over to the wall.

‘I've had two instruction sketches blown up here,’ he said. ‘One showing the instrument panel in its entirety, the other showing the actual lever for the front doors. On the first sketch the switch for the door circuits is marked with number 15 and the door lever with number 18. The lever is therefore to the left of the wheel, in front of and obliquely below the side window. The lever itself, as you see from the second sketch, has five different positions.’

‘Who could make head or tail out of all this?’ Gunvald Larsson said.

‘In the horizontal position, or position one, both doors are shut,’ Ek went on unperturbed. ‘In position two, one step upward, the rear entrance door is opened, in position three, two steps upward, both doors are opened. The lever also has two positions downward-numbers four and five. In the first of these, the front entrance door is opened, in the second, both doors are opened.’