Longman Dictionary of Contemporary English
The Collaborative International Dictionary
Open verdict \Open verdict\ (Law) A verdict on a preliminary investigation, finding the fact of a crime but not stating the criminal, or finding the fact of a violent death without disclosing the cause.
Wikipedia
The open verdict is an option open to a coroner's jury at an inquest in the legal system of England and Wales. The verdict means the jury confirms the death is suspicious, but is unable to reach any other verdicts open to them. Mortality studies consider it likely that the majority of open verdicts are recorded in cases of suicide where the intent of the deceased could not be proved, although the verdict is recorded in many other circumstances.
Usage examples of "open verdict".
If they considered the evidence on this point insufficient, they could return an open verdict.
The inquest into the parents' deaths returned an open verdict, and to this day the Home Office believes that the children were abducted by their parents' murderers.