John Longo, 57, pleaded guilty Thursday to one charge of producing material depicting the sexual exploitation of a minor.
Authorities said the retired Pennsylvania Turnpike worker asked a coworker to take sexually explicit images of a 12-year-old girl and email them to him.
Prosecutors said Lisa Renze sent him the pictures between June 2009 and November 2010. She pleaded guilty in April to producing child pornography.
Longo is being detained pending his Jan. 22 sentencing in federal court in Pittsburgh.