Nick Reiner, 32, who remains jailed without bail, pleaded not guilty to murder charges on Feb. 23.
In court Wednesday, a date was initially expected to be set for a hearing to determine if there is enough evidence for him to stand trial. But attorneys said they were still gathering evidence in the case, and a prosecutor said autopsy reports were still pending.
Another hearing for Reiner -- who appeared in court in a yellow jail top and blue jail pants -- was scheduled for Sept. 15.
Rob and Michele Reiner were found stabbed to death in their Brentwood home on Dec. 14.
The night before, Nick Reiner -- who had been living on his parents' property -- got into an argument with Rob Reiner at a holiday party and was seen acting strangely, sources told ABC News. Nick Reiner was taken into custody hours after the bodies were discovered.
Jake Reiner, the couple's eldest son, recently spoke out, describing his parents as his "guiding lights" and "the most giving people I have ever known."
L.A. County District Attorney Nathan Hochman told reporters outside court following the Feb. 23 hearing that his office would be "looking at all aggravating and mitigating circumstances" and that Nick Reiner's attorney has been invited to present written and oral arguments before a decision is made on whether to seek the death penalty.
Rob and Michele Reiner's son Jake Reiner speaks out in new statement: 'My living nightmare'
Rob and Michele Reiner's son Jake Reiner speaks out in new statement: 'My living nightmare'
"It will be subject to not only a rigorous analysis, but many of the most experienced individuals in the D.A.'s Office with death penalty experience will be helping me evaluate that information," Hochman said.
The L.A. County Office of Medical Examiner classified the couple's deaths as homicides, with both dying from "multiple sharp force injuries."
Court sets hearing dates in D4vd murder case
Meanwhile, in another high-profile murder case, singer D4vd appeared in a downtown L.A. courtroom Wednesday, where a judge set dates for upcoming hearings in the case. A preliminary hearing for D4vd, whose real name is David Anthony Burke, was scheduled for May 26. A status hearing was set for May 12.
D4vd, whose real name is David Burke, is charged with killing 14-year- old Celeste Rivas Hernandez, whose dismembered body was found in the trunk of his Tesla at a Hollywood tow yard. He has pleaded not guilty to the charges against him.
Last week, prosecutors said they found what they described as a significant amount of child sexual abuse material on his phone. They said more than 40 terabytes of evidence was found on computers, tablets and iCloud, adding that sheer volume could slow the progress of the case.