The man accused of setting fire to a camp in Dachau was convicted last week in the US of setting fires in a trailer, a restaurant and an apartment in California.
The man, Michael Dachai, has been jailed since his arrest on 22 October.
He is due to be sentenced in New York next week.
It was not immediately clear why he had been charged in New Jersey but a spokesman for the US attorney’s office in Manhattan said in a statement: ‘The FBI was notified of the allegations and has commenced an investigation into these allegations.
‘The investigation has been closed.’
On his Facebook page, Dachari posted that he was ‘deeply sorry’.
He said he had ‘lost control’ and had been using drugs.
But prosecutors argued that Dacharis use of the drug ketamine and alcohol had led to the deaths of his wife and two of their children.
The US attorney for the western New Jersey district, Andrew Zaccaro, said that Daccari was an ‘incompetent, unqualified cook’ and that the deaths were the result of ‘a long-term pattern of drug use and alcohol abuse’.
His lawyer, Daniel Hamermesh, said Dacharas ‘long history of alcohol and drug use, including a history of violent acts, made him incapable of providing for his family.’
He said that in 2013 Dachars children were taken away by his parents and he was placed in foster care.
A judge in the western Pennsylvania district said that the allegations against him were ‘absolutely without merit’.
‘This case has been presented to the judge who has already ruled on it, and this is the final decision,’ said a spokesman, Robert P. Wiegert.
The attorney for one of Dachais children, Katherine Kohn, said she was devastated by the verdict.
‘I don’t know what he is going to do, what he’s going to say, but I do know that he will be going to jail for the rest of his life,’ she told NBC.
‘He was a good boy, he loved the outdoors and the outdoors is his passion.
He would go fishing, he would hunt and he would shoot.
He was a wonderful person, he was a great father and I’m devastated.’
Dachare was arrested at the end of October on suspicion of first-degree murder, arson and unlawful possession of a weapon.
He has pleaded not guilty to all of the charges.
The Associated Press