Brought in several times before to audition for various guest appearances, Debbon Ayer, Rob Morrow's real-life wife, guest-starred as the victim of a home invasion.
Later, Don, Nikki, and FBI Special Agents David Sinclair (Alimi Ballard), and Colby Granger (Dylan Bruno) stake out the next target predicted by Charlie's equations.
The team rescue the couple inside, Sara and Gil Fisher (Debbon Ayer and Michael Gaston), as the home invasion takes place.
Charlie rushes to the hospital, joined by his girlfriend and colleague Dr. Amita Ramanujan (Navi Rawat) and his and Don's father Alan Eppes (Judd Hirsch).
A partial print found at the scene leads the team to Los Angeles Unified School District's 2007 Teacher of the Year Tom Kardum (Shea Whigham), who is a suspect in the disappearance of an investment banker.
The team then learns that he was Slobodan Radovic, a Serbian war criminal who had murdered the home invaders' families in Croatia.
The FBI team also learns that the investment banker, through an intermediary who is found murdered during the investigation, wanted to pay Radovic in diamonds.
After seeing a still from a confiscated surveillance video, Charlie replicates a key to the investment banker's safety deposit box, which is at a jewellery store.
Earlier in the season, series co-creators/executive producers Cheryl Heuton and Nicolas Falacci developed a storyline in which David became a leader.
[2] On the "Crunching Numb3rs: Season Five" bonus feature, series regulars Alimi Ballard and Sophina Brown reflected on the impact of Don's stabbing on David, Colby, and Nikki.
[3] Although he had previously done so on several occasions, casting director Mark Saks rarely offered roles to actors' family members or friends.