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.
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.