Nick Reiner Indicted For Murders of Parents Rob and Michele, With Special Circumstance

Nick Reiner has been indicted for allegedly murdering his parents -- Rob and Michele Reiner -- and special circumstance allegations have been added.

According to the Los Angeles District Attorney's Office ... Reiner pled not guilty Wednesday to two counts of murder with the special circumstance allegations of multiple murders and murder by means of lying in wait after a grand jury indictment was unsealed. He also faces another special allegation that he personally used a dangerous and deadly weapon, a knife.

Special circumstances can increase potential penalties for Nick if he's found guilty at trial. It's unclear if prosecutors plan to pursue the death penalty, but it opens the door for the D.A. to pursue capital punishment if Nick is convicted.

Reiner's lawyer, public defender Kimberly Greene, declined to comment following the hearing. He has a pretrial hearing set for September 15.

District Attorney Nathan Hochman said in a statement, "This was a profound betrayal by someone who was loved and trusted by the very people he is accused of killing. The indictment unsealed today also adds a special circumstance allegation that the defendant committed the murders by means of lying in wait. We hope that by having a grand jury return an indictment in this case it will bring us one step closer to a trial and achieving justice."

As you know ... Reiner was arrested in December after allegedly stabbing both of his parents to death in their West Los Angeles home.

He's been held in custody since the brutal killings ... and was disciplined just a few months ago for allegedly getting "hostile" with L.A. jail staff.