Nicholas Helman, of Hatboro, pleaded guilty on Monday to charges he laced a card with ricin and mailed it to his ex-girlfriend's new love interest earlier this year.
Hazmat crews had to be called to his home in the 100 block of Byberry Road to decontaminate the property.
Also on Monday morning, prosecutors filed new charges of solicitation of murder, terroristic threats and related offenses.
Investigators say Helman is accused of writing a letter threatening to harm prosecutors, witnesses and the investigating detective.
He was formally arraigned in Warrington. His bail is set at $10 million.
A preliminary hearing is set for January 12th.