The scowl Callie was directing my way was beginning to chill my bones. ‘OK, tell me what I’m missing?’

‘Mum wasn’t the one who did the initial stabbing. She took the knife out of Dan’s back. The fact that it’s already covered with blood smears shows that. According to the coroner’s report, Dan was stabbed once in the jugular and once straight through his heart, from the back. Whoever stabbed him would’ve been covered in blood. You can’t stab someone in the jugular and not get blood over the weapon and all over your hands. The single drop of blood falling from the blade indicates that Dan’s heart wasn’t beating when Mum removed the knife or there would’ve been blood all over her. Look. There isn’t a speck of red on her.’

Frowning, I took a closer look. Callie was right …

‘I was there, remember? No one at that dinner table had blood on their hands.’ At least not literally. ‘Callie, all this proves is that your mum washed her hands first before returning to the rest of us.’

‘Tobey, we’re watching Mum replace the knife and try to wipe her fingerprints off it, but there’s nothing here to show that she stabbed Dan in the first place. Look closely. There’s blood on the handle, but none of it was transferred to Mum’s blouse when she wiped it, so the blood must’ve dried by the time she tried to remove her fingerprints. And this is before any trip to the bathroom to supposedly clean up.’

I pressed rewind and played the clip at half-speed.

‘Why doesn’t your recording start from the time Mum entered Dan’s study?’ asked Callie, interrupting my viewing.

‘I asked the same question of George. He told me the security camera must’ve been set to restart at a certain time, which turned out to be when your mum had the letter opener in her hand,’ I replied.

‘How convenient for the killer,’ said Callie.

‘Well, they couldn’t’ve known Sephy would be in the room when the recording restarted. That was just bad luck on your mum’s part,’ I replied.

I took back my phone to watch the recording again from the beginning. ‘It’s not conclusive proof of your mum’s innocence though,’ I argued.