Corporal Mullen joined the force in 2001. He attended the Montgomery County Police Academy and graduated with academic honors.

 Corporal Mullen is the department patrol rifle instructor, defensive tactics instructor and K9 handler.

He holds certifications in oleoresin capsicum spray, extendable baton, hand to hand defensive tactics, narcotic interdiction, SFST practitioner and K9 handler certification through the Northeastern Police K9 Association.

Corporal Mullen received a merit service award in 2002 from the Macungie Police Department and two life saving awards from the Macungie Police Department in 2004 and 2006.

He was promoted to Corporal in 2006.