I was alarmed because he is not allowed to go outside and we have to be careful around open doors because he is nevertheless known as our Escape Cat.
But then as I was about to rush outside to try to retrieve him I got a better look.
It wasn't Blackwell but a visitor we had not seen before with longer hair.
I called to him and he stopped and gazed at me for a moment as I got one blurry picture shot through a screen window.
I think regular readers of this blog will see the resemblance to Blackwell but he was right behind me, enjoying a patch of sunlight.
Since I've been opening my window and putting up the shade he is either up on the shelf behind my computer monitor helping to monitor the birdbath or, when the sun shines in, enjoying the "warm spot" on the floor.