Arson experts ruled out technical faults as the cause of the fire, which broke out last September in the player's rented Grünewald villa and caused millions of euros worth of damages.
Breno, 22, was initially questioned as a witness, but soon became a key suspect in the incident and spent time in custody under suspicion of arson.
The findings, which have been turned over to the district attorney's office, place renewed suspicion on Breno himself, according to Süddeutsche Zeitung.
Prior to the fire, Breno, whose full name is Vinicius Rodrigues Borges, had been getting psychiatric help at the renowned Max-Planck Psychiatry Institute, which the media put down to chronic knee pain the player was known to suffer from.
A spokesman for the district attorney's' office said, “There is no reason that we would drop the arrest warrant.”
Breno was jailed in September, but was released with conditions once state prosecutors became convinced that Breno would not flee to his native Brazil.
Breno's attorney, Werner Leitner, refused to comment on the report, saying the investigation is still ongoing.
But the newspaper reported that investigators are expected to complete their work soon and a psychiatric report – which has not yet been filed - is expected to help rule whether Breno will have to face the charges in court.