[3] Mullin graduated from Wilbert Tucker Woodson High School in Fairfax, Virginia where he was active in theatre and speech and debate.
He traveled to Virginia's Hampton Roads region for his college education, graduating from Christopher Newport University in 2004.
[2] Mullin shortly after his election sponsored "Heaven's law" to protect children from child abuse; on December 30, 2019 he introduced two bills for the upcoming session concerning protocols for referring schoolchildren to criminal justice authorities.
[7] Mullin served as the chair of a key subcommittee that can conduct hearings for rewriting Virginia's criminal code.
[8] On March 12, 2020, he noted progressive reforms passed in that Virginia legislative session, which passed legislation offering additional protections for 14 and 15 year old defendants, as well as ending drivers license suspensions for unpaid fees and fines, raising the felony threshold to $1,000, decriminalizing some marijuana offenses, reforming criminal discovery effective in the summer, expanding deferral options for certain misdemeanors, opening parole opportunities for certain "Fishback" defendants, and allowing jurors to be told about criminal punishment ranges.