The 63-year-old suspect in the bombing that rocked Nashville on Christmas morning was killed in the blast.
The explosion destroyed Anthony Quinn Warner's motor home and damaged more than 40 businesses.
FBI forensic experts matched DNA samples recovered from the scene to that of Warner, whose home in nearby Antioch was searched on Saturday by federal agents.
"We've come to the conclusion that an individual named Anthony Warner is the bomber and he was present when the bomb went off and that he perished in the bombing," said Donald Cochran, US Attorney for the Middle District of Tennessee.
Officials said it was too early in the investigation to discuss the suspect's motives.
Warner's motor home, parked on a downtown street of Tennessee's largest city, exploded at dawn on Friday moments after police responding to reports of gunfire noticed it. They heard music and a recorded message coming from the vehicle warning of a bomb.
The explosion in the heart of America's country music capital injured three people. It damaged an AT&T switching centre, disrupting mobile, internet and TV services across central Tennessee and parts of four other states.
As investigators followed up on hundreds of tips from the public, they searched Warner's home on Saturday and visited a Nashville real estate agency where he had worked on computers.
The owner of the agency, Steve Fridrich, told the Tennessean newspaper that for four or five years Warner had come into the office roughly once a month to provide computer consulting services. This month Warner told the company in an email that he would no longer be working for them, without giving a reason, Mr Fridrich said.
"He seemed very personable to us – this is quite out of character I think," Mr Fridrich told the newspaper.
Nashville Mayor John Cooper said on the CBS News Face the Nation programme on Sunday that local officials felt there had to be some connection between the bombing and the AT&T building.
Damage to the switching centre was so extensive that AT&T teams had to drill access holes into the wreckage to connect generators to critical equipment, as well as pump one metre of water from the basement.