HATBORO, Pa. (AP) — A man sent a birthday card laced with the deadly poison ricin to a romantic rival in hopes of winning back his ex-girlfriend, authorities said.

Nicholas Helman, 19, was arrested at his home in Hatboro, outside Philadelphia, Wednesday on an attempted murder charge and other counts, authorities in Bucks County said.

Helman told a Target store co-worker earlier this month that he sent the toxic card to his ex-girlfriend's current boyfriend, investigators said. The co-worker notified police, who called the recipient's home and spoke to his mother, who said her daughter was outside getting the mail at that moment. Authorities then went to the home to confiscate the card.

Investigators returned to Helman's neighborhood Thursday and recovered a suspicious package from under a gas main cover. The package was intact and will be tested to determine its contents. Authorities said there was no danger to the public and did not release any other details.

Helman was questioned March 7 and told investigators only that he had coated the card with a substance that resembled anthrax, authorities said in an affidavit of probable cause. He said he intended to scare his ex-girlfriend in hopes of reconciling with her, police said. He initially was charged with terroristic threats and harassment and spent four days behind bars before making bail.

Authorities said Helman had ingredients for making ricin, a poison that occurs naturally in castor beans, but that initial tests didn't turn up the toxin itself. Authorities then sent the card away for more lab tests, and prosecutors were told Tuesday that traces of ricin had been confirmed on the card, the district attorney's office said. Police accompanied by hazardous materials teams and the FBI then arrested Helman.

Bucks County District Attorney David Heckler told The Philadelphia Inquirer that the toxin was "very potent."

"He made ricin, and if you lick that card, you're dead," he said.

Court documents don't list an attorney for Helman, who was jailed without bail after his arraignment Wednesday night. He has a March 27 preliminary hearing.

His father, Douglas, told The (Doylestown) Intelligencer that he knew nothing about the charges. He said his son had been good at science and math in school and made Eagle Scout last year.