He had not been answering calls and text messages, and he did not show up to his dentist appointment. His wallet, credit cards, glasses and cash were all found in his room.
Until almost a week later.
Authorities searched for Bernstein for almost a week with assistance from drone pilots and found his body near a brush after it had been partially exposed by rainfall.
The suspect: his classmate from high school.
Samuel Lincoln Woodward, 20 was arrested in the killing of 19-year-old Blaze Bernstein. Woodward told investigators that he picked up Bernstein from his home in Lake Forest, California, and they drove to a Hobby Lobby parking lot to "hang out" and "catch up", the Orange County Register reported, citing a court affidavit.
Bernstein, authorities have said, disappeared late on the evening of January 2 after he and a friend went to a park in the Foothill Ranch area of Lake Forest to "hang out".
When the Sheriff's Department initially interview Woodward, he said that he dropped Bernstein off at the park and waited for an hour in the vehicle.
News of Woodward's arrest comes two days after Bernstein's identity was confirmed as the body found the day prior. That was the last time Bernstein was reported to have been seen, authorities said. The friend could not recall the girlfriend's last name or address.
An affidavit obtained by the Orange County Register revealed that two days after Bernstein disappeared, Woodward had scratches on his hands and dirt under his fingernails. These were from a "fight club" he was involved in, according to the report.
Woodward was taken into custody for investigation of homicide after DNA evidence linked him to the death of Bernstein, who was a sophomore at UPenn in Philadelphia. And as he was walking inside the sheriff's headquarters during an interview, he kept himself from touching the doors by pulling his jacket over his hand. He said Woodward was arrested based on inconsistencies in his comments to investigators.
"Finally", Bernstein's mother, Jeanne, tweeted shortly after the arrest.
"Nothing will bring back my son so we ask the world to please honor Blaze's memory by doing an act of kindness today - don't wait - do it now", the grieving mom told the Los Angeles Times. "My only hopes are that he will never have the opportunity to hurt anyone else again and that something meaningful can come from the senseless act of Blaze's murder". Investigators also said they would not release details on the condition of Bernstein's body or what may have occurred at the park.
It was the only homicide reported in Lake Forest in at least the past four years, according to authorities. Bernstein's father, Gideon Bernstein, had also worked with friends of the family to conduct independent drone operations.
Bernstein was visiting relatives in Orange County while on winter break from school.