Tune in to “NCIS” on CBS, Tuesday, January 17th at 8:00 PM to see Stephen Mendel guest star as Retired NCIS Special Agent F. Pettis. Pettis is a retired NCIS special agent who, enjoying retirement, is reluctant to come back and assist NCIS in solving the mystery of a 15-year-old cold car that eluded his team so long ago… In this episode, after spotting the brother of an NCIS Most Wanted suspect, Gibbs immediately assumes a former alias and goes undercover with their infamous anti-government militia group while Bishop and Reeves work together on an off-the-books investigation.