JACKSONVILLE, Fla. -- Police arrested a man Tuesday for having child pornography -- pictures he says he downloaded from computers at a Jacksonville public library.

The man -- who is homeless -- was arrested for trespassing. Officers found pictures of naked children when they searched his bag.

The man says he downloaded the images while using a computer at the Mandarin branch library.

Jacksonville's public libraries have a filtering system on all of their computers, but their spokeswoman told Channel 4 Tuesday evening that no system can block all porn sites all of the time.

"Unfortunately, because so many of these pornographic Web sites are being put out there every day, they can't always catch everything immediately as they come up," Stacie Bucher said. "They are one of the best filtering systems, but, again, nothing is foolproof."

Library officials said they've asked the Jacksonville Sheriff's Office to give them the name of the Web site the man accessed, so they can ask the company that provides the Internet filters to add that site to their restricted list.