Maybe it is just semantics, but entertain this for me.
The police and FBI investigate many things. Sometimes the investigation concludes with a finding that there isn't enough evidence, or in fact the target is innocent. Does the investigator forward those files to a prosecutor?
Hell no.
When an investigator forwards a file, that is way of saying "there is probable cause a crime has been committed. Here are the facts." The investigator is done, other than appearing to testify before a GJ or in conjunction with a trial.
In other words, every time an investigator forwards a file, he is recommending an indictment, at least to the extent his competency allows him to make recommendations.
But the law vests all, 100% of the decision to proceed (and how to proceed) with a prosecutor, not the investigator. It is totally out of line for an investigator to "recommend an indictment." There are no "prosecutors in the FBI." Investigation and prosecution are two very separate functions.