JEFFERSON CITY, Mo. -- Not much is normal about the Missouri grand jury responsible for deciding whether to charge a suburban St. Louis police officer for fatally shooting Michael Brown.

Not the length of deliberations, not the manner in which it has heard evidence, not the way its work could be made public. Then again, the case itself is unusual.

Ferguson Police officer Darren Wilson, who is white, shot the black, unarmed 18-year-old shortly after noon Aug. 9 in the center of a street. As Brown's body lay there for hours, an angry crowd gathered. Riots and looting occurred the next night. In the following days, police responded with tear gas and smoke canisters.

The Associated Press spoke with a veteran prosecutor and criminal defense attorney in Missouri about the typical grand jury process -- and the ways the Brown case differs.

Extra time

At the time of Brown's shooting, a St. Louis County grand jury already had been hearing cases and was scheduled to disband Sept. 10. In one of the first indications Brown's case would be different, a judge extended the jurors' service until January, the maximum amount of time allowed.

Whereas a typical case might be presented to a grand jury in a single day, this case has stretched over three months.

No specific charge

It's fairly common in Missouri for a prosecutor to file a complaint charging an individual with a crime, then go later to a grand jury asking it to indict the person for that offense. In this case, St. Louis County Prosecutor Bob McCulloch hasn't publicly suggested any particular charge against Wilson.

Numerous witnesses

Often, a grand jury hears testimony from just a few people, such as police investigators who summarize evidence. In this case, McCulloch has said "all witnesses with any relevant evidence" were being summoned to testify.

Types of witnesses

Typically, a prosecutor presents only witnesses who would aid his quest for an indictment. The target of the inquiry does not typically testify. But Wilson testified to the grand jury.

Recordkeeping

There often is no record of exactly what's said in Missouri grand juries. That's because only the jurors, witness and prosecutor are in the room. In this case, however, McCulloch's office has said the proceedings are being recorded and transcribed.

Secrets made public

What's said in a grand jury typically remains secret, though when an indictment is issued, the evidence can be aired at a trial.

If Wilson is not indicted, McCulloch said he will ask a judge for permission to release the grand jury evidence.