I found an article that references his health during the Christine Thorton investigation. Assuming it's accurate, seems when he was interviewed in 2016, he was supposedly frail & feeble, but definitely remembered, and enjoyed playing games during a 2 hour interview.
You know what? A 2 hour interview would do most people in who weren't 75, let alone frail & confused. I bet he's acting to some degree. He's continuing to fool many people.
Here's a snippet:
When they showed Alcala the photo of Christine astride the motorcycle, his eyes scanned the image he had taken so many years ago. He traced the outline of her body with a finger.
“You could see him replay that day in his head,” Jeff said later. “He knew what happened out there.”
How Kathy Thornton solved her sister’s 39-year-old murder case