While he apologized for the secrecy surrounding his relocation, he did not provide details about how -- or when -- he arrived in Guatemala.
Guatemala's foreign minister said Wednesday that officials there did not know how McAfee came into the country.
There is no registry of McAfee entering legally at any official border crossing, Foreign Minister Harold Caballeros told reporters. He declined to comment on whether his country would offer McAfee asylum.
Belize won't seek his extradition, Martinez said.
McAfee founded his namesake computer security software in 1987, initially running it out of his home in California. He sold his stake in the company in 1994 and moved to Belize in 2008.
A 2009 story in the New York Times indicated that his fortune had plunged to $4 million from its $100 million peak, largely because of the real estate and stock market crashes that hit his investments.
In February 2010, he started QuorumEx, which is trying to "reinvent the way modern medicine combats and disarms pathogenic bacteria," according to its website.
McAfee will hold a news conference Thursday, according to his blog. He is expected to reveal the next move in the international mystery.