What is necessary for a witness to make a timely complaint for rehabilitation?

For a witness to make a timely complaint for rehabilitation, it is essential that the witness has been previously impeached. Impeachment can involve questioning the credibility of a witness, typically through prior inconsistent statements or evidence suggesting bias or inability to recall events accurately. If a witness has not been impeached, there isn't a perceived need for rehabilitation, as the integrity of their testimony has not been established as questionable.

In the context of rehabilitation, the goal is to restore the witness's credibility after it has been challenged. This process often involves introducing evidence or testimony that counters the claims made during the impeachment. Thus, the fact that the witness was previously impeached creates a foundation for them to present rehabilitative evidence or testimony to mend their credibility in front of the court.

The other options do not accurately reflect the requirements for making a timely complaint for rehabilitation. New testimony does not necessarily correlate with the need for rehabilitation; a written statement is not a requirement for rehabilitation; and while a witness typically testifies before any rehabilitative measures can be taken, the critical factor is whether they have been impeached.