The Toronto Sun says 22-year-old Elton McDonald described himself as the "main digger" for the 10-metre long underground chamber that captured international attention last week.
The paper quotes McDonald as saying it took about five months to build the bunker, that he had planned to add a few more rooms and put in a TV.
He reportedly told the Sun the chamber had been there more than two years when police were alerted to its presence in January.
Toronto police said Monday that two men built the tunnel as a place to "hang out" and that no criminal charges would be laid.
The discovery was announced a week earlier, prompting many to speculate online about the chamber's origin and purpose.
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