How long do investigations usually last?

Up to five years. If you are a target of an investigation, it may be possible to eliminate you as a target or make you a smaller player. Many federal defense attorneys offer a free consultation. My suggestion is to contact one soon to discuss the various strategies when you are a target of a federal investigation. Good luck.

It depends on the substance of the investigation. It depends on how many individuals involved in the investigation. There is no rule of thumb.

Here is a link to an article that will answer most of your questions about federal drug investigations: http://www.jensendefense.com/articles/drugconspiracy.html

Under 18 USC § 3282 a Grand Jury must issue a Federal indictment within five (5) years after the defendant committed the offense. But for conspiracy, the time does not start until: 1) the conspiracy ends, 2) a participant’s last open act furtherance of the conspiracy, or 3) the defendant’s withdrawal from the conspiracy before the objective is attained.