“With the room locked from the inside? You don’t think it was an accident? He could have fallen over, bashed his head. Maybe he stood up to get something from the cupboard.”

Her gut screamed that it wasn’t an accident, but her training forced her to consider every option. She cast her professional eye over the scene, searching out possibilities that she might have missed. There was a small mirrored unit on the wall next to the bath. Possible to reach from the bath, but it would have been a stretch, and yes, it was likely that if you tried that, you might slip. One of the doors on the cupboard was open slightly. She could see how it might happen. Yet that scenario could easily be ruled out: if the man was reaching for the cupboard, he would have fallen out of the bath onto the floor, not backward into the water.

Joanna considered the velocity of a simple slip-and-fall scenario, if it were the case that he had fallen in the right direction. “I don’t see how a person could injure themselves that badly by falling over in the bath. The water would have broken the fall to some extent.”

Thrupp stepped forward to inspect the rim of the bath. “I thought the tap was running,” he said. “That’s why the leak happened, and the neighbor was alerted, correct?”

“Yes.”

“So, might have been a dry bath at the time, or only enough water in it to make him lose his footing. Therefore it would have been a harder fall.”

“Do you get in the bath before it’s full?” she said. “I don’t. Something hit the guy hard enough to damage the skull, break the skin, and cause him to go unconscious. I’m not sure a fall would do it.” She shuddered at the memory of the place where her hand had supported his head, the cold-porridge feeling of mashed tissue.

On the bathroom tiles, Joanna spotted something that stuck out slightly. Almost the same white as the vinyl, a small triangular piece of something, like a chip from a smashed mug handle.

“What about this?”

Thrupp bent over and squinted at the object. “I can’t tell what that is. A bit of tile that’s come off somewhere? Doesn’t give us much.”

“Well, that’s the point. We can find out, sir, if we have the forensic team. I’m convinced there was someone else here.”

“Based on what? I can’t just take your word, Jo. You need something to back it up. Say there was someone else here. How did they get out?”

Above the bath there was a high window. Seven floors up, there was no way an assailant could have used it as an escape route. They turned their attention to the door.