NCIS: Los Angeles' Marty Deeks knows all the interrogation tricks in the book, and his time on the other side of the glass is making life exceptionally difficult for the LAPD's Internal Affair's investigator.

'NCIS: LA' Season 7 Spoilers: Deeks Takes A Beating In 'Internal Affairs' Promo, Is He Guilty?

Deeks' (Eric Christian Olsen) fellow cops believe he is responsible to the murder of his former partner, but the shaggy-haired detective isn't acquiescing to their fishing expedition in a new sneak peek from E! Online (watch video here).

"The first instinct he has is this is a witch hunt, and whatever role Deeks played in this is a different role than whatever it is that they're trying to pin on him," Olsen told E! Online. "There are so many clouded moments in the events that it's hard to define the character by what he did or did not do."

'NCIS: LA' Season 7 Spoilers: Will Densi Survive Deeks' Arrest? Eric Christian Olsen Isn't So Sure

Unfortunately, there is DNA evidence against the NCIS liaison. Combined with the fact that he previously reported Boyle for violent behavior, Deeks is currently IA's No. 1 suspect. Perhaps his OSP pals can find the real killer.

Find out more when NCIS: LA airs "Internal Affairs" this Monday at 10 p.m. ET on CBS.

Tags: NCIS: LA NCIS: Los Angeles television CBS