Sometimes witness do not want to give information because they become afraid of what can be happen to them, sometimes it can be influenced by age, physical characteristics also emotions. Some witness may not desire to give any information because they do not want to get involved, or may fear any contact with a law enforcement agency and some just do not want to do anything that would aid the police. Some witnesses maybe reluctant to be cooperative or be specious of the motives of the interview sometimes a language barriers.
No. No one has the right to impede justice. If they have information that is material and relevant to the case, they do not have the option to withhold it. They may be questioned as a "hostile witness" or they may be ordered by the judge to testify. If they refuse they can be held in contempt of court and jailed and/or fined.
It is your choice, but if you have material information that would aid either the prosecution OR the defense, and choose to withhold it, you may be treated as a "hostile witness" or, even held in contempt of court for withholding evidence.
Information gathered by someone who did not take part or witness is called second hand information.
A Material witness is person with information about an alleged criminal. The most recent version, allows a material witness to be held giving criminals proceedings.
In some legal systems, the offender may have the right to see the witness statement, but usually personal information is redacted to protect the witness's privacy. The court usually determines what information can be disclosed to the offender.
The attorney wants to find out what the witness knows. He might ask what they saw, what time it happened and other stuff. He needs the information to decide whether the witness is good or whether it would be a waste of time to use the witness. If he called a witness to the stand and the witness didn't have any information, didn't see or hear anything - it would waste time in court.
This is hearsay, which is a secondary source of information that is not allowed.
Information gathered by someone who did not take part in or witness the event is called hearsay.
A once credible witness may become not credible if they are found to have a bias or personal interest in the outcome of the case, if their testimony is inconsistent or contradicted by other evidence, or if they have a history of providing false information or being unreliable in the past. Additionally, factors such as emotional state, memory issues, or manipulation can also affect a witness's credibility.
Everything about the offense they can possibly remember.
Heresay
Why would you want to go after the witness and not the deputy? Who says the witness was intimidated? Can it be proven? Were there witnesses to the alleged intimidation? What were you charged with, if anything? Not enough information given in the question to answer it.