The Tatung Institute of Technology said it punished Chen Ing-hau in April 1998 when the virus he wrote began to damage an inter-college data system, said Lee Chee-chen, the institute's dean of student affairs.
Chen, then a senior, was given a demerit but not expelled.
The college did not impose a more severe punishment because Chen warned fellow students not to spread the virus, Lee said.
Lee said he was not sure how the virus ended up causing so much destruction a year later.
The Chernobyl virus is known in Taiwan as the CIH, after Chen's initials.
Chen graduated last summer and is serving Taiwan's two-year compulsory military service, Lee said.
Officials of the Bureau of Criminal Investigation said they would seek permission to question Chen.
The unusually destructive virus, timed to strike on April 26, the 13th anniversary of the Chernobyl nuclear disaster, tries to erase a computer's hard drive and write gibberish into its system settings to prevent the machine from being restarted.
Turkey and South Korea each reported 300,000 computers damaged Monday, and there were more elsewhere in Asia and the Middle East. Damage was less extensive in the United States, where fewer than 10,000 out of 50 million computers in the country were affected.