In an evening news conference Monday, the suspect was identified as 24-year-old Harry Burkhart. Burkhart was held on $250,000 bail.
The suspect may have been motivated by a deportation battle. The German national told authorities upon his detention, "I hate America," according to ABC News sources, and the suspect's mother reportedly had a deportation hearing that took place in Los Angeles County about a week and a half ago.
At least 12 new fires popped up on Monday morning, bringing the total number of arson fires to 53 since Friday. One firefighter was injured fighting one of the fires. No other injuries were reported.
No further arson fires were reported since the arrest.
Police on Sunday released surveillance footage of a person of interest in connection to the fires, but it was unclear if the man arrested on Sunset Boulevard and Fairfax Avenue was the person in the footage. Officials said it was too early in the investigation to tell.
During a search of the man's minivan, a suspected incendiary device was found in the man's vehicle, sources told ABC News. The suspect was the fourth person brought in for questioning.
Authorities said the suspect was uncooperative and would be asked to sit for a polygraph test.
Shervin Lalezary, a volunteer reserve sheriff's deputy who makes just $1 a year, was the one to pull him over about 3 a.m.
There were at least 12 new fires overnight in Hollywood, Hollywood Hills and Studio City, starting shortly after 1:30 a.m. A fire on Alfred Street near La Cienega Boulevard damaged four cars and three apartment units.
Two people were arrested early Thursday morning for four arson fires and one attempted fire that were determined to be unrelated to the Friday, Saturday and Sunday fires, according to ABC News. Samuel Arrington, 22, was charged with arson of an inhabited dwelling and was held on $75,000 bail. Alejandro Pineda, 55, was charged with arson of property and held on $50,000 bail.
The German national was arrested for fires set Friday, Saturday and Sunday. He was charged with one count of arson, but more charges are expected.
Burkhart's apparently angry his mother, Dorothy, could be deported after a hearing last week in Los Angeles County.
ABC News has learned that after the arrest, Burkhart told investigators "I hate America."
Neighbors said mother and son live in a Hollywood apartment building next door to Galina Larimoda.
Galina Larimoda speaks Russian, but told Eyewitness News through a translator that Burkhart knocked on her door Sunday and seemed very angry.
Larimoda said he didn't seem "completely normal."
Shlomo Elady works next to Burkhart's apartment. He said he cut his hair about a week ago.
"How come I didn't see in his face any anger, any sign of depression?" Elady said.
"This has been a very trying time for Los Angeles," said L.A. City Councilman Tom La Bonge. "I can't remember any time ... this type of action that's taking place."
In nearly all of the fires, flames were ignited in or around vehicles and then spread to structures, causing hundreds of thousands of dollars in property damage.
Fire investigators set up a Facebook and Twitter page to update the public on the latest developments on this case. Officials are asking the public to speak up if they know anything about the arson fires. Anyone with information is urged to call the LAPD Arson Hotline at (213) 486-6890.