Samuel Woodward, 20, a high school classmate of Bernstein's, was brought into custody Friday afternoon during a traffic stop and charged with suspicion of homicide in the death of the teenager.
Bernstein was visiting home for winter break from Penn when he went missing on Jan. 2.
His corpse was found Tuesday in what Orange County Undersheriff Don Barnes described on Friday as “a shallow grave in the brush on the outer perimeter” of Borrego Park near the victim’s Foothill Ranch home.
Barnes refused to discuss what murder weapon was allegedly used.
He also wouldn't reveal Woodward's alleged motive or the condition of Bernstein's body.
But he did say that autopsy results were pending.
The discovery of Bernstein's body, Barnes said, was helped along by the recent downpour of rain that managed to move some of the soil that was covering him.
"The rains helped move some of the dirt," he said.
Orange County District Attorney Tony Rackauckas said that he expected prosecutors to work through the holiday weekend to hand down an indictment by Tuesday.
The prosecutor said that the entire incident was "very tragic" and that Bernstein "had a life in front of him that is now extinguished."
He added that both the Bernstein and Woodward families "are good people" whose lives "have been turned upside down" as a result of the alleged fatal attack.
Initially, Barnes said that Woodward was cooperative and answered questions by homicide investigators about Bernstein’s disappearance.
But that questioning broke down and Woodward soon requested an attorney at which point the interview stopped, Barnes said.
"He came in and was cooperative and answered questions," Barnes said of the initial questioning of Woodward.
What's more, soon after Bernstein went missing, Barnes said that Woodward allegedly changed the color of his hair.
On his booking description at the Central Jail where Woodward is being held his hair is listed as "blond" and his occupation is "Nerf Games."
Barnes said there were also "inconsistencies" in Woodward's story.
The gaps during questioning and also DNA evidence matches, Barnes said, led investigators to levy charges against Woodward.
It was ultimately DNA evidence that helped investigators initiate the arrest of Woodward.
"We were able to today, through DNA, to tie Mr. Woodward to Mr. Bernstein," Barnes said Friday.
Barnes also praised the work of investigators who he said "were able to invalidate portions of [Woodward's] story."
Early on in the search for Bernstein, investigators determined that he left behind his wallet, eyeglasses, cash and credit cards and missed a dentist appointment.
Barnes said Bernstein also didn’t respond to numerous calls or texts by his family.
That led them to fill out a missing person's report.
Homicide investigators soon took over the case, and they believe Bernstein was last seen alive on the night of Jan. 2 when he allegedly met up with an unnamed friend and the pair drove to multiple places before ending up at the park, Barnes said.
It's unclear if the unnamed friend is Woodward or not.
The friend, according to the affidavit, allegedly told investigators that they planned to hang out and Bernstein mentioned meeting another friend of theirs from high school.
Upon arriving at the park, the friend allegedly told investigators that Bernstein left the car and walked off.
In the affidavit, the friend said he waited for an hour for Bernstein to return to the car and then tried to reach him on Snapchat. When that failed, the friend said he went to his girlfriend's house and then returned to the park a few hours later to look for Bernstein.
Police said, according to the affidavit, during their questioning, he couldn’t remember his girlfriend's last name or where she lived.
Investigators also noticed several scratches and abrasions on the friend's hands which he claimed were from a "fight club," mentioned by Barnes and also detailed in the affidavit. The friend also appeared to have dirt under his fingernails. When asked about that, the friend said he fell into a dirt puddle. Investigators also noticed the friend appeared to "breathing heavy, talking fast, and visibly shaking."
Authorities said the friend's story was fairly consistent, the Register reported.
The Ivy League student's mother, Jeanne Pepper Bernstein, tweeted today, "Finally."
"My thoughts are: Revenge is empty. It will never bring back my son," she said. "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. Now Do Good for Blaze Bernstein."
After the Penn sophomore's body was found, his father, Gideon Bernstein, was emotional at a news conference, calling his son "a brilliant, colorful and charismatic man."
Embracing his wife, the grieving father called her his "rock," adding, "Our children are so strong and we just want to see resolution."
Dr. Valarie Swain-Cade McCoullum, vice provost for university life at Penn, said in a statement this week, "I came to know Blaze, and I grieve his passing."
She said Blaze Bernstein "loved the written word."
He was the incoming managing editor of the student-run food magazine, wrote opinion columns for the student newspaper The Daily Pennsylvanian, and was also a copy associate for the paper's arts and culture magazine, she said.
"I realize these losses have the potential to affect many, many members of our Penn family," she said. "Hug your friends and roommates. Practice self-care and empathy. Celebrate who and what you have on this special campus. Find unity and strength, together."