RENO, Nev.?Four of six Microsoft employees who touched a contaminated letter tested negative for anthrax, Nevada health officials said Sunday.

Preliminary test results show the two others exposed to an anthrax-contaminated letter sent from Malaysia to a Microsoft office have also tested negative for inhalant or airborne anthrax. Five Microsoft employees and a family member were exposed.

The final results of those nasal swab tests won?t be known until Monday, said Washoe County health officer Barbara Hunt.

A third test on pornographic pictures in a letter sent from Malaysia to the office tested positive for anthrax, Nevada Gov. Kenny Guinn said Saturday.

State officials have sent the pictures to the Centers for Disease Control and Prevention in Atlanta for further testing, Guinn said.

Microsoft officials contacted health officials Wednesday about the letter, which had been sent to the Microsoft Licensing Inc. office.