Nick Reiner will be charged with two counts of first-degree murder with special circumstances for the killings of his parents, Rob Reiner and his wife Michele Singer Reiner, who were found dead in their home over the weekend, Los Angeles County District Attorney Nathan Hochman announced Tuesday. 

"Their loss is beyond tragic and we will commit ourselves to bringing their murderer to justice," Hochman said at a news conference alongside Los Angeles Police Chief Jim McDonnell. He added that this type of case is "the most serious charge the DA's office can bring against anyone."

The district attorney said the charges carry a maximum sentence of life in prison without parole or the death penalty, but said his office hasn't made a decision in this case. 

Nick Reiner was arrested on Sunday without incident in the Exposition Park area, near the University of Southern California, Los Angeles Deputy Chief of Detectives Alan Hamilton said. He is being held without bond. 

Two sources familiar with the incident told CBS News the couple were found with multiple stab wounds. Hochman confirmed a knife was used in the killings and said one of the special circumstances in the case is that the murder was committed with a deadly weapon such as a knife. 

An attorney for Nick Reiner said his client would not be in court Tuesday due to medical reasons, The Associated Press reported.  Greg Risling, a spokesperson for the district attorney's office, also told CBS News Los Angeles that his "understanding" is that Nick Reiner "is a medical miss out today." 

Hochman said during the news conference that Nick Reiner is currently going through medical clearance, which is standard procedure. Once he is cleared, the district attorney said, he will appear in court for arraignment. 

So far police have not released details about the evidence in the case, a possible motive or what led them to arrest Nick Reiner. At the briefing, they declined to answer questions about his mental state or whether he has made any statements to investigators.

The Reiners attended a party the night before the killings at Conan O'Brien's, where Rob and Nick Reiner had a brief but loud argument, sources who were at the party told CBS News. 

On the day the couple was found dead, they had plans with their longtime friends Michelle Obama and former President Barack Obama, according to the former first lady.  

"We were supposed to be seeing them that night, last night, and we got the news," said Michelle Obama during an interview on "Jimmy Kimmel Live!" Monday night.