The mystery man, listed in court papers as John Doe, is alleged to have assumed the identity of Jason Evers, a three-year-old boy who was murdered in 1982.
John Doe was arrested last month after the investigators with the U.S. State Department cross-checked the name on his passport with death certificates and discovered the name he was using was not his own.
According to Jason Evers' father, Bob Evers, the impersonator used Jason Evers' name for 14 years undetected, since applying for a birth certificate in 1996. Prosecutors say there is no connection between the John Doe and the murder of the three-year-old boy--another man was convicted of the murder and imprisoned.
Bob Evers told CBS News he thought it was a "sick joke" when he first heard an imposter had been using his son's name. At the time he had been working on a petition to keep his son's murderer, who is up for parole June 2, behind bars.
"I'd like to know who he is and how he got my son's name," Bob Evers said of John Doe, adding that he doesn't want his son's name associated with a criminal.
Authorities say the mystery man, who worked as an Oregon Liquor Control Commission investigator for eight years, refuses to reveal his true identity.
"Mr. Doe has been in custody now for almost a month and the Diplomatic Security service is using every available resource to find the true identity of John Doe. Despite these efforts, today we still do not know who he is," said Stacie Beckerman, the assistant U.S. Attorney prosecuting the case.
According to the poster seeking information that was released today, the man is reported to "speak 'street' type Spanish", be a "master chess player" and "be of above average intelligence."
On Monday, U.S. Magistrate Judge Donald Ashmanskas ruled the John Doe could be released to his Bend, Or. home until his arraignment June 14, but that decision was appealed by prosecutors who argued he could pose a flight risk.
On Wednesday, Hamilton County, OH Prosecutor Joseph T. Deters announced he will also file charges of identity fraud against the mystery man.
"We are going to find out who this guy is. And we will find out why he stole this beautiful little boy's name," Deters said in a press release.
To date, mystery man John Doe is in the custody of U.S. Marshals where he will remain until his arraignment, according to the Portland, Oregon U.S. Attorney's Office. Anyone with information about this man's true identity is encouraged to contact the Diplomatic Security Service Seattle office at 206-220-7721.