The suspect in the same case he is prosecuting? It might make a good plot for a fiction book and technically it IS possible, but I seriously doubt it.
Not necessarily.
An Indictment, an Accusation, or an Information.
Prosecutor
In a criminal law case there are 6 parties involved. These parties include the victim, the defendant or suspect, the defense attorney, the prosecutor, the judge, and the jury.
The District Attorney became the lead prosecutor in the murder trial.
Generally a law degree is required
The suspect becomes the defendant during the arraignment, which is the initial court appearance following arrest. During this stage, the defendant is formally charged and enters a plea. The prosecution may also present preliminary evidence to establish probable cause for the charges, which is essential for moving the case forward.
To become a prosecutor, you typically need to complete a bachelor's degree (4 years), attend law school (3 years), and pass the bar exam in your jurisdiction. In total, it can take around 7 years of education and training to become a prosecutor.
Briefly, to start, in order to become a Federal prosecutor (otherwise known as an "Assistant U.S. Attorney") you will need a J.D. Degree from an ABA accredited law school and three (3) years prior litigation experience. That's the short answer.
When they're formally charged.
its evidence. it doesn't mean everything but what is collected during a criminal investigation that helps prove the suspect/prosecutor committed the crime. Much of it is collected at the crime scene, if there is one.
I suspect that takes a combination of competence with the subject and practice.