Cybersleuths track "Melissa".

New infections from the "Melissa" e-mail virus dwindled Tuesday, while a number of self-appointed cybersleuths tapped their technical skills to find clues that Melissa_s author has struck before. Meanwhile, several large companies were still laboring to restart e-mail systems that were overwhelmed and forced to shutdown as Melissa spread. Lockheed Martin Corp., the No. 1 defense contractor, won_t open its e-mail system to the outside world until today, when it_s certain safeguards are working. Lucent Technologies Inc., the biggest phone-equipment maker, was bringing its e-mail online Tuesday, one computer at a time. The Melissa virus surged across the Internet in file attachments sent by users of Microsoft Corp._s Word 97 or Word 2000 programs. People who use Microsoft_s Outlook program to keep e-mail addresses automatically passed the virus to 50 people on their address list by opening the attachment that listed a number of Internet pornography sites. That e-mail explosion overwhelmed many corporate and Internet computer servers. Security experts said despite the decreased impact, computer users should remain vigilant. The FBI, which is investigating the source of Melissa, refused to comment on its progress. But in a twist unique to cyberspace, a number of software experts and amateur investigators used their tech savvy to match digital fingerprints on Melissa with those of a user, or groups of users, that may have struck before. R. Smith, president of software firm Phar Lap Software, of Cambridge, Mass., said the clues he found link the virus to a still-unidentified writer who uses the computer handle "VicodinES". Smith said he thinks the virus writer distributed it using an account stolen from America Online 15 months ago. Smith used a digital fingerprint that is embedded in documents written with Microsoft Office programs such as Word and Excel to match Melissa with the AOL account. The same account had been used in December 1997 to post a virus similar to Melissa. Smith said he passed the information he gathered on to the FBI.