Nick Reiner in Court for First Time After Parents' Murders

Nick Reiner -- who is charged with killing his parents, Rob and Michele Reiner -- appeared in court today for the first time since the couple's unspeakable murders.

Nick was seated behind glass in a Los Angeles courtroom Wednesday for a very brief appearance ... and he did not enter a plea. His arraignment was continued to Jan. 7 ... he remains held without bail.

Nick was wearing a suicide-prevention smock in the courtroom, according to multiple reports, and before the hearing, the judge ruled that media could not shoot video or snap photos of Nick.

During the hearing, Nick spoke only once ... the judge asked him to confirm he was waiving his right to a speedy arraignment and Nick replied, "Yes, your honor."

After the hearing, Nick's attorney, Alan Jackson, said the case was a "devastating tragedy" for the Reiner family. He said there are "very complex and serious issues associated with this case" that need to be thoroughly reviewed and examined.

Prosecutors have charged Nick with two counts of murder with the special circumstance allegation of multiple murders. He also faces a special allegation that he personally used a dangerous and deadly weapon ... a knife.

Alan told the court it's "too early" for Nick to enter a plea ... and he said the defense and prosecutors were in agreement on pushing back Nick's arraignment until next month. The L.A. Times reports two other lawyers appeared with Jackson and Reiner Wednesday morning.

Nick's first day in court was originally set for Tuesday, but was taken off the books because he didn't have medical clearance. Despite the court appearance being delayed, there was still a major update to the case Tuesday when Los Angeles County District Attorney Nathan J. Hochman announced Nick has been charged with two counts of first-degree murder.

Hochman added that if Nick is convicted, the death penalty is on the table.

TMZ broke the story ... sources told us Nick was acting very strange Saturday at Conan O'Brien's Christmas party ... not interacting much with guests, and his attire was out of place ... Nick was moping around in a shabby sweatshirt and seemed high on something. We're told Nick got into a loud argument with Rob at the party, and Rob left with Michele shortly after.

Nick lived at home with his parents, but he opted to check into a hotel at around 4 AM Sunday, using his credit card. The reservation was made for just a day, but Nick never formally checked out.

When the staff came into his room later Sunday morning, they found the shower "full of blood" and blood on the bed.

That afternoon, Rob and Michele were found dead in their Brentwood home with multiple stab wounds. The couple's daughter, Romy, is the one who discovered their bodies and called 911. She told police her brother Nick was "dangerous" and should be considered a suspect.