Is the sentence OK?

You need to indicate the possessive: The witness' testimony and material evidence are verified, all pointing to his offence

Also, "are verified" probably ought to say "have been verified." All in all, though, it's an obscure and rather strange sentence. You're talking about a witness, but then refer to "his offence." In English usage, someone who is being tried for a crime, although he or she might be called as a witness, is usually referred to as "the accused."

What I am trying to say is that there is no doubt about the case and the accused should be sentenced to jail, because a witness' testimony and material evidence have been verified. I don't know if have made it clear.

OK, let's rewrite the sentence:

The witness' testimony and the material evidence have been verified, all pointing to accused's offence.

I would change "offence" to "guilt".

OK, THANK YOU.