State Superior Court Judge Harry Carroll did not set bail for Choi pending further investigation.
Choi, of Valley Stream, N.Y., is charged with killing 27-year-old friend Han-Il Kim, then waiting hours in Kim's room before killing his mother and uncle.
Authorities said evidence in Kim's diary led them to California, where the 32-year-old was arrested Sunday.
Authorities believe a fight over money led to the stabbing deaths.
Assistant Bergen County Prosecutor Wayne Mello said Kim and Choi were in Kim's room May 4 snacking on a plate of fruit when Choi grabbed a paring knife and stabbed Kim in the neck.
Mello said Choi then hid Kim's body in a closet and draped a blanket over him, then stuffed clothing in Kim's bed to make it look as if he was asleep. Early the next morning, Choi killed Kim's mother, 47-year-old Yoo Bok Kim, when she came upstairs looking for her son.
Choi told Yoo Bok Kim that her son was in bed, but she noticed her son's hands sticking out of the closet, Mello said. Mello said Choi stabbed her, then ran downstairs and encountered Yoo Bok Kim's brother-in-law, 70-year-old Doo Soo Seo, and stabbed him to death.
Before fleeing, Choi broke into a nightstand in Yoo Bok Kim's room and stole $30,000, according to Mello. He then flew to Los Angeles under an assumed name, and was arrested at the Commerce Casino near Los Angeles with $14,000 in chips on him.
Choi was a frequent gambler in casinos in New Jersey and California, according to those who played with him.
"Whatever the biggest games in here were, he would play," Dave Cardenas, a regular in the high-stakes poker den at the Borgata Hotel Casino & Spa told The Star-Ledger of Newark for Wednesday's newspapers. "He played crazy. He'd bet and raise constantly. We call those maniacs."
Kyle Burnside of Mays Landing told the newspaper he played poker against Choi at the Borgata and at the Commerce Casino.
Burnside said Choi "always lost" at the Borgata, losing hands of $4,000, $8,000 and more. In California, Burnside said, "he was usually winning."
Cardenas said Choi sometimes dropped $10,000 or $12,000 at a time in Atlantic City. But he and fellow gamblers were shocked at his arrest.
"Everyone was absolutely surprised," Cardenas said. "No one thought this guy could do something like this."
Prosecutors have not said whether they believe Choi's gambling was related to the murder charge against him.
A Borgata spokesman did not immediately return a message seeking comment Wednesday.
