Federal agents say they found similarities between a pipe bomb used by a Georgia man in 1972 and bombs that killed a federal judge and an attorney last year.

The bombs' construction was unlike that of any of 10,000 bombs that federal agents have dissected, Agent Frank P. Lee of the federal Bureau of Alcohol, Tobacco and Firearms said in an affidavit made public Wednesday.Similarities included the use of "square end plates with threaded rods extending from plate to plate within the pipe and secured with nuts," the February search warrant affidavit said.

That construction "is unique to the explosive device" Walter Leroy Moody Jr. was convicted of having in 1972 and three of four mail bombs sent in December 1989, Lee said.

He said he based the conclusion on a computer search of ATF and FBI records describing more than 10,000 bombs nationwide since 1975.

One of the December bombs killed Judge Robert Vance of the 11th U.S. Circuit Court of Appeals in Atlanta. Another killed Savannah lawyer Robert Robinson. Two other bombs were safely intercepted at the 11th Circuit offices and at the Jacksonville, Fla., office of the NAACP.

Moody, 56, of Rex, is a suspect in the slayings but has not been charged. He's being held without bail on unrelated charges.

Moody and his wife, Susan, 27, are charged with obstruction of justice, bribery and witness tampering for allegedly trying to erase his 1972 conviction for possessing the pipe bomb that injured his ex-wife, Hazel.