7 CBS Sync Facts From "The 3rd Choir" S6 E4

Mattias was first introduced in Season Two's “Absolution,” accompanied by two goons, and checking the pulse of Sander Lee, a man he had gunned down. Callen and Sam stumbled on the scene and a firefight ensued. Sam killed one of the goons, but Mattias and the other escaped through a back door.

In Season Four's "Lohkay," Kensi found out that Deeks used to be a stripper in order to pay his room and board.

John Heard, who plays NCIS: Los Angeles' Special Congressional Investigator Michael Thomas, has a prior relationship with the District of Columbia. Not only was John born in Washington, D.C., but he also played Congressman Roger McCourt on the CBS show "Person Of Interest."

Meet J.R., a head chef with Bruce's Catering and part of the NCIS: Los Angeles family.

Nate Getz is the Operational Psychologist brought in from undisclosed field assignments to analyze coworker moods. He reads comic books and graphic novels. He completed college in three years; and he earned his Master's degree and a Doctorate in two years.

Arkady Kolcheck worked as a security consultant for mining companies and oil pipelines before starting his own consultancy firm in the U.S. and later moving to Los Angeles.

The last time we saw Hetty shoot somebody was in Season Two. Hetty shot and killed members of the Comescu crime family in Season Two's finale, "Familia."

For more awesome facts from CBS sync watch the full episode online here.