U.S. prosecutors say the mystery man of Seattle was sentenced Friday to 30 months in prison after living under more than 20 assumed names for nearly 30 years.

Assistant U.S. Attorney Johanna Vanderlee said at the hearing that Scott Shain, 53, Seattle, had "an obsession with firearms and an obsessive use of identities of dead people."

Shain was so prolific at assuming the names of the departed that it took investigators a few weeks after his arrest in March to nail down exactly who the mystery man they had in custody really was, authorities said.

Shain was picked up after Canadian officials tipped off the FBI that someone was trying to obtain a birth certificate of one Dwayne Spill, a British Columbia native who had died in 1982.

The U.S. attorney's office in Seattle said in a written statement that when agents contacted the supposed Dwayne Spill in Seattle, he identified himself as "Robert Lowe" and said it was a "William Gee" who had requested Spill's birth certificate.

It turned out Spill, Lowe and Gee were all Scott Shain, who had allegedly slipped away in 1989 in order to avoid a gun-related charge in Colorado.

Prosecutors said Shain told the court he wanted to "do some good" after he served his time on fraud and identity theft charges but mercifully said nothing about making a name for himself.