to be kept silent

Can one say
a. The witness was murdered to be kept silent.
b. The witness was murdered to serve as a lesson to others.
?

Many thanks.

What about: a) “They murdered the witness to get/make him fall silent.”?
I would agree with b).

Or: b. “The witness was murdered to provide a lesson for others.”

Why not this way?

a. The witness was murdered to prevent his/her appearance from tendering evidence against the accused.

b. The witness was murdered so that it would serve as a warning to others.

a) The witness was murdered to guarantee his silence.
The second original sentence in message #1 above is fine as it is.

You can’t really ‘guarantee’ silence from someone who is dead. You need to suggest the idea of prevention.

Which is why in my recast the prevention is the murder.

How about “The witness was murdered to make sure he remained silent / didn’t talk.”?

Yes, I agree that works. It’s the gist of my sentence.