Harry Burkhart, 24, a German national, has pleaded not guilty to 100 arson-related charges in connection with 49 blazes set in Hollywood between Dec. 30 and Jan. 2.
He remains jailed on $7.5 million bail. If convicted of all charges, he faces more than 80 years in prison.
Most of the fires began in automobiles but often spread to homes in Hollywood, West Hollywood, Sherman Oaks and surrounding areas.
The fires did at least $3 million in damage, officials said.
The first fire was set the day after Burkhart showed up a hearing in his mother's case and went on an anti-American tirade, according to authorities.
Police also say that, just hours after the first fires erupted, Burkhart went to the German consulate looking for help getting his mother out of jail.
A guard allegedly saw the Burkhart put a fire-starting device on the floor, and he snapped a picture of it.
Investigators said the picture links Burkhart to many of the blazes, which were started with a common briquette used to start fires in a fireplace or grill.
They also said they have DNA evidence found at one of the fires that implicates Burkhart, as well as witnesses who placed him as near the scene of several fires.
Dorothee Burkhart has insisted that her son is innocent, and that he is mentally ill.
A medical doctor in Vancouver told CNN that Harry Burkhart suffered from severe mental illness when she examined him in 2010.
Family physician Dr. Blaga Stancheva was asked to examine Burkhart to support a claim that he was unable to show up for a small-claims court case.
Stancheva said she and other doctors, including a psychiatrist, diagnosed Burkhart with "autism, severe anxiety, post-traumatic stress disorder and depression."
Burkhart lived with his mother in Vancouver before moving to Los Angeles.
Authorities in Vancouver were probing a possible link between Burkhart and at least a dozen unsolved property arsons in Vancouver last year.
Burkhart was arrested on Jan. 2 after a Los Angeles sheriff's reserve spotted his minivan driving near Sunset Blvd. and Fairfax Ave.
Police said detectives found materials that could have been used to set fires inside Burkhart's van.
Investigators also found news articles about the arsons inside his apartment, according to court papers.
Burkhart apparently had some additional clippings from German newspapers about a string of car fires near Frankfurt last year.
German prosecutors have said that Burkhart is being investigated in connection with a fire at a house owned by his family in Marburg on Oct. 14.
Burkhart surfaced as a suspect when he filed an insurance claim after the blaze, which did about $50,000 in damage, Marburg prosecutors said.
Federal immigration officials said Burkhart was in the United States on a visa that expired Jan. 18. No visa could be found for his mother.
In May, Burkhart's mother, Dorothee Burkhart, was extradited back to her native Germany where she faces fraud charges.
She was ordered into the custody of the U.S. Marshal, without bail, until she's turned over to authorities in Germany.
Burkhart was arrested in December 2011 on an outstanding warrant from Germany.
According to court papers, she is wanted on 19 counts of fraud "committed on a commercial basis and as a member of a gang, and breach of trust."
She is accused of falsely claiming a $10,000 payment on breast augmentation surgery, and failing to return security deposits to renters.
Burkhart escaped from German custody by crawling out of a hospital window and fleeing Europe, her attorney said.
It's believed her arrest an imminent deportation may have triggered her son's alleged arson spree.