“The fact that we cannot find Alexey is especially alarming because last week he became ill in his cell: he became dizzy and laid down on the floor. The colony staff immediately came running, lowered the bed, laid Alexey down and put [him] on an IV,” [Kira Yarmysh] said on X.
[…]
“I perfectly understand that, like many political prisoners, I am sitting on a life sentence. Where life is measured by the term of my life or the term of life of this regime,” [Navalny] said in a statement.

Navalny knew something like this would probably happen; he became a personal enemy of Putin and even as a prisoner he remained a symbol of defiance against Putin.

I hope Navalny is okay, but I fear the worst.