These days
competence is all it takes; a quality in VERY short supply among Federal Government officials these past few years!
Seriously, there are several factors;
How difficult you are to capture
How likely you are to commit further crimes
How many people are likely to be affected by your crimes, and how negatively they will be affected
How likely you are to endanger federal officials, plans or property (in that order)
How badly you have embarrassed or annoyed the FBI or other federal officials
How much fun it would be to punish you by prolongued tickling in bondage (that last one is just wishfulk thinking on my part).