Twenty-one-year-old Christian Neith failed to appear for a bail hearing Monday before a Northampton County judge.
Neith had pleaded guilty in August to smuggling a handgun into the county prison last December. The gun was found several days after being hidden behind a cabinet and sparked a four-day lockdown.
The hearing was scheduled to determine if Neith's bail should be modified following a hair of failed drug tests.
Defense attorney James Burke said he expected his client to turn himself in.
The failure of authorities to find Neith's concealed weapon prompted security procedure changes at the prison.