Suspicion is the twelfth episode in NCIS Season 4 and also the eighty-second episode of the entire NCIS series.
A Marine intelligence officer is found dead in a hotel room in the small town of Edenvale, prompting NCIS to investigate. Unfortunately, when they arrive, the NCIS team discover that the Sheriff's Department have a suspect- an Iraqi national who had just moved to the town a few months earlier with the team also discovering that Edenvale is a town where prejudice and suspicion is common among the town's population.
- Abby reveals that when she was eleven years old, she had a paper round.
- It's revealed that Gibbs brings his own coffee grind with him whenever he goes on overnighters.
- The song playing when Abby test-fires the gun in her lab is VETO - You Are A Knife.
|Leroy Jethro Gibbs||Mark Harmon||NCIS Special Agent in charge of the NCIS Major Case Response Team.|
|Anthony DiNozzo Junior||Michael Weatherly||Senior Special Agent and second-in-command of the NCIS Major Case Response Team.|
|Ziva David||Cote de Pablo||Mossad Liaison to the NCIS Major Case Response Team.|
|Abigail Sciuto||Pauley Perrette||Chief Forensic Specialist, NCIS.|
|Timothy McGee||Sean Murray||Junior Agent of the NCIS Major Case Response Team.|
|Jennifer Shepard||Lauren Holly||NCIS Director. Despite being credited, Holly does not appear in this episode.|
|Donald Mallard||David McCallum||Chief Medical Examiner, NCIS.|
|Jeanne Benoit||Scottie Thompson||Tony's girlfriend.|
|Bradley Raines||Mark Derwin||Marine Corps Intelligence Officer and Lieutenant Rihama Shaheen's immediate superior.|
|Tom Barrett||Brian Howe (actor)||Sheriff of Edenvale who assists the NCIS team in investigating Lieutenant Rihama Shaheen's murder.|
|Tyler Barrett||Jon Curry||Edenvale Sheriff's Deputy and also Tom's younger brother.|
|Ruby Rae||Lynsey Bartilson||Edenvale forensic scientist who processed the evidence at the crime scene where Lieutenant Rihama Shaheen's body was found.|
|Waseem al-Fulani||Cas Anvar||Iraqi resident of Edenvale and who was formerly Captain Waseem al-Fulani of the Iraqi Republican Guard. Received U.S. citizenship in exchange for highly valuable information on the Iraqi insurgency.|
|Daryl Hardy||John Beasley (actor)||Masoud's nosy neighbor.|
|Patrick Carmody||Victor Raider-Wexler||Guest at the hotel and also the man who found Marine Lieutenant Rihama Shaheen's remains.|
|Asad Al-Qutaji||Dylan Ramsey||Iraqi national.|
|Youssef Zidan||Kunal Nayyar||Iraqi national. Uncredited role.|
|Rihama Shaheen||Necar Zadegan||A First Lieutenant in the United States Marine Corps and a Marine Corps Intelligence interpreter who is also the main murder victim. Uncredited role.|