St. Louis County Prosecuting Attorney Robert McCulloch  (Tom Gannam/AP)

Prosecutors plan to begin presenting evidence in the shooting death of Michael Brown to a grand jury  Wednesday morning, the county prosecutor’s office said Tuesday.

“We know this is of interest to a lot of people around the country,” Edward Magee, spokesman for St. Louis County Prosecutor Robert McCulloch, told The Washington Post. “We’re going to do this fairly and also attempt to do it in a timely manner.”

It is unclear what charges prosecutors might seek or whether Darren Wilson, the Ferguson police officer who shot and killed Michael Brown, will ultimately be charged.

The 12 members of a St. Louis County grand jury will meet in secret to determine whether the evidence presented by prosecutors is sufficient to charge someone with a crime.

McCulloch met with his lead prosecutors  Tuesday at 1:30 p.m. to review the status of the investigation and the evidence that has been gathered so far. Meanwhile, in Ferguson, protesters and some elected officials have been calling on McCulloch to step aside as the prosecutor and have an independent special prosecutor handle the case involving Wilson.

In a grand jury investigation, a prosecutor alone determines whether to recommend specific criminal charges be brought. The jury can ask questions to determine whether the evidence warrants the charges, while no outside lawyers for the victim or the defendant can be present or ask questions.

McCulloch’s office confirmed that they have been in contact with an attorney for Wilson and received a full statement of Wilson’s version of events on the day that Brown died.

The FBI and St. Louis County police have conducted some joint interviews with witnesses who were uncomfortable talking to police alone, officials said. The FBI has also canvassed for witnesses in the Ferguson neighborhood  Saturday and Sunday, which resulted in several new interviews  Monday, and McCulloch has copies of those statements.

Magee said that while the investigation is not complete, it has reached a critical mass of information. McCulloch’s office is not yet in possession of ballistics tests, he said. Magee declined to comment on the results of any drug testing that was conducted on Michael Brown’s body.