But Swedish researcher Fredrik Bjoerck said traces on the internet pointed to a German exchange student living in Australia.
Officials say they entered the house in the capital, Manila, after obtaining a search warrant.
Police originally thought the main suspect was male but now say they are looking for a female computer school student from a middle-class family.
The FBI and Interpol helped track the virus to the Philippines through an electronic trail left by the rogue e-mails.
US security experts said clues in the virus code pointed to a student at a computer college in the Philippines.
But Swedish researcher Fredrik Bjoerck said traces on the internet pointed to a German exchange student living in Australia.
The virus caused a flood of e-mails with the alluring subject line ILOVEYOU to course through computer systems in more than 20 countries on Thursday.
At least seven variations appeared soon after, one masquerading as an e-mail joke, another as a receipt for a Mother's Day gift.
Anti-virus software maker Symantec said the latest variant of the virus poses as a warning message from their technical support team. Infected e-mails have the subject line Virus ALERT! and should be deleted.
Estimates of the worldwide damage from the virus range from hundreds of millions of dollars to $10bn, mostly in lost work time.
But officials in Manila have raised the possibility that the suspect might not be responsible for the computer attack.
"It was only the computer used to launch the virus that was traced but anybody could use that computer," said an official.
"The user here is invisible, it could be anybody. The difference is that the person we have identified is the registered owner of that computer."
Experts say the virus is likely to engender more variants in the coming weeks.
It only affects systems running Microsoft Windows with Windows Scripting Host enabled. Computers using Apple's operating system or Linux are not affected.
Although the virus seems to have started in the Philippines, systems there and in much of Asia have escaped largely unscathed as several markets were on holiday last week.