A local man says he was scammed by Lopez, who claimed he was a ticket broker.
The two were in contact through the online classifieds website and arranged to meet at the Cantina Lounge in Fullerton, where the victim bought two tickets for Game 2 for $900.
When the victim tried to get into the arena for the game, he was denied entrance and told the tickets were fake.
The victim called police and reported the crime.
Boston officials contacted the Fullerton victim, who positively identified Lopez as the man who sold him the tickets.
Boston police say Lopez used the aliases Steve Williams and Jason Martel.
Detectives are asking anyone who feels they were scammed to contact the Fullerton Police Department at (714) 738-6880.