BOSTON -- Boston police and FBI agents said Friday they have conclusively proved that Clark Rockefeller, the Boston father accused of kidnapping his daughter last month, really is a German national who came to the United States close to 30 years ago.

Unedited Video: FBI Confirms Rockefeller's Identity | Defense Attorney Reacts

In an afternoon news conference, FBI agents said Rockefeller's fingerprints, analyzed at FBI headquarters at Quantico, Va., show he is really Christian Karl Gerhartsreiter, an immigrant born in West Germany in 1961 who's been named a "person of interest" in the disappearance of a California couple in 1985.

"By matching the major case prints Boston Police took from this suspect 10 days ago to a piece of paper he touched 27 years earlier, the FBI’s fingerprint technicians brought science to bear where mere suspicion had prevailed," Suffolk County District Attorney Dan Conley said.

The prints were taken from a wineglass Gerhartsreiter used in Boston just before he allegedly kidnapped his 7-year-old daughter Reigh "Snooks" Boss and fled to Baltimore, where he was arrested after a massive international search.

The glass prints positively match the prints on Gerhartsreiter's U.S. immigration documents and a print obtained after his Baltimore arrest, law enforcement authorities said.

Gerhartstreiter, 47, is being held without bail in Boston, charged with kidnapping and assault and battery for allegedly snatching the child during a supervised visit in which a social worker was injured trying to prevent the alleged abduction.

"I don't think any of us could have predicted the turns this case would take," Conley said.

"Gerhartsreiter is at the center of the longest con I have ever seen in my professional career," he added. "But although the story is something out of a crime novel or a movie, the underlying offense is very real and very serious. At the heart of this case is a little girl. This defendant put her at risk, put her in fear and threw her family into turmoil. That he is her natural father does not excuse his actions. Massachusetts law is very clear on that point," Conley said.

The prosecutor said authorities will now amend the complaint that's been filed against Gerhartsreiter to reflect his true name and additional charges may be added in the future.

"It's important to remember the children, like the victim in this case. Defenseless boys and girls are at the mercy of the adults who are around them. When they go missing it is very tragic and it happens with all too much frequency," Conley said.

"We're very happy that this case has worked out the way it has and we've been able to definitively prove that the various identities used by this individual are one and the same person," Boston Police Commissioner Ed Davis said.

Gerhartsreiter's attorney, Stephen Hrones, said he doesn't see that the positive identification of his client makes any significant difference to the case at hand.

"You don't need to know his birth name in order to prosecute him for these offenses. Not at all. You can prosecute him as Rockefeller," he said.

He said authorities may now decide to level a misdemeanor charge against Gerhartsreiter for giving a false name to a police officer, but he said that's not a serious development.

"He wasn't changing names to defraud anyone. Anyone can change their name," Hrones said.

He has maintained that his client doesn't remember anything about his childhood in Germany and very little about living in California.

Gerhartsreiter was known as Clark Rockefeller during his 13-year marriage to Sandra Lynn Boss, whom he divorced last year. His visit with his daughter Reigh was his first since the couple split at the end of 2007.

He allegedly abducted the child during the July 27 visit, getting a ride to New York city and then fleeing to Baltimore, where he had purchased a $400,000 carriage house near a marina.

Police traced him to the carriage house a week later and arrested him after a real estate agent tipped them to his whereabouts.

The child, who had not been harmed, was safely reunited with her mother, a management consultant who has been living with Reigh in London since the divorce.

The massive search for Gerhartsreiter and Reigh Boss was stymied when investigators found he had no records -- no driver's license or Social Security number or any other legal documentation.

During the course of the investigation they learned he had used numerous aliases after arriving in the United States as a foreign exchange student in the late 1970s, including Rockefeller, Christopher Chichester, Christopher Crowe, Charles Smith and Chip Smith.

A family in Berlin, Conn., said Gerhartsreiter lived with them for a time while attending the local high school, but he soon moved. Authorities said he then moved to Wisconsin, where he married a 22-year-old woman before abandoning her to move to California.

In San Marino, California authorities said, he lived under the name Chichester in a guest house belonging to John and Linda Sohus, a couple who mysteriously disappeared in 1985 without a trace.

Human bones were found in the back yard of the Sohus house nearly 10 years later by a crew digging a swimming pool, but were never tested to see if the remains belonged to either of the Sohuses.

Although California police want to talk to Gerhartsreiter about the case, he has refused to speak with them and no charges have been filed against him in connection with the couple's disappearance.

The FBI said they were contacted by the Los Angeles sheriff's department back in 1994-95 for help in finding Christopher Chichester after the remains were discovered in the Sohus yard. They said they confirmed at that time that Chichester likely came to the country as Gerhartsreiter and was probably using the name Crowe.

A fingerprint given by a Christopher Crowe has also been matched to Gerhartsreiter's fingerprints, the FBI said.

Last week in Germany, Gerhartsreiter's brother Alexander identified pictures of him for newspaper reporters as the long-lost brother who left his Bavarian hometown as a teenager to go to the U.S. He said the family had lost touch with Gerhartsreiter when he stopped contacting them around 1985.