The site, http://www.joe2006.com, suffered an apparent DoS attack before Tuesday's face-off for the Democratic spot on the ballot in November's general election.
Lieberman's campaign manager, Sean Smith, said on MSNBC's "Hardball" program this week that the site was hacked by political opponents.
Earlier this week, a statement standing in for the crashed site called on Lamont, now the Democratic senatorial candidate while Lieberman runs as an independent, to denounce the hacking.
Dan Geary, a site administrator for the campaign said a web analysis of the server indicated that a DoS attack focused on specific portions of the site, according to media reports.
Connecticut Attorney General Richard Blumenthal and the FBI will investigate the alleged attack, according to press reports.