Police in Wisconsin tracked down an alleged teenage stalker in Australia after he unwittingly left the details of his computer's address on a pizza delivery website, WISN-TV reported Thursday.

The 17-year-old boy from Western Australia began an online friendship with a 14-year-old Grafton girl, sending her an unusual array of gifts. In April, a Domino's pizza showed up on her doorstep.

"They were uncertain where the pizza came from. Subsequently, the 14-year-old girl received an email stating, 'How did you like the pizza?' That was from the person in Australia," said Grafton police investigator David Wenzler.

When the girl became concerned and blocked the Australian teen on social networking site Facebook, he became angry and began to threaten her via email and text, police said.

One text read, "If you thought ultimate love was bad, wait till you see ultimate hate. I'll ruin your life. I know exactly where you live."

Police in the US and Australia tracked down the boy using his computer's IP (internet protocol) address, which they obtained from the Domino's pizza delivery website.

The boy -- who has behavioral issues -- was arrested and may face stalking, fraud and harassment charges, according to a police report.