A more thorough explanation:

Instantaneous crime refers to a crime that is committed in a very short period of time, usually in a matter of seconds or minutes. It is a crime that occurs suddenly and without warning.

• A bank robbery where the thief enters the bank, demands money, and leaves within a few minutes.
• A hit-and-run accident where the driver hits a pedestrian and immediately drives away.

These examples illustrate how an instantaneous crime can occur quickly and without warning. In both cases, the crime is committed in a matter of seconds and the perpetrator is gone before anyone can react.

Instantaneous death refers to a death that occurs instantly, without any warning or suffering. It is a sudden and unexpected death that happens in an instant.

Instant case refers to the case that is currently being discussed or considered. It is the case that is currently under review or being debated.

Instanter is an adverb that means instantly or at once. It is used to indicate that something needs to be done immediately or without delay.

For example, if a judge orders a defendant to file a motion instanter, it means that the motion must be filed immediately and without delay.