Mike Renko was a Field Agent in the NCIS Office of Special Projects in Los Angeles.
Despite regularly spending most of his time out in the field, working undercover, Renko occasionally arrived back at OSP HQ to help the main team led by G. Callen.
Renko did this up until his death in the line of duty during the NCIS: Los Angeles Season 3 finale episode, "Sans Voir Part 1" with his death devastating the OSP team.
NCIS Season 6Edit
Like his OSP colleagues, Callen, Sam Hanna, Nate Getz, Kensi Blye and Eric Beale, Renko made his debut appearance in Episode:Legend (Part 1) where during an operation involving the NCIS: Office of Special Projects and Agents Leroy Jethro Gibbs and Timothy McGee who are members of the Washington D.C. NCIS: Major Case Response Team, Renko posed as "Mattie Rae", a man who sought to buy weapons from a mysterious arms dealer.
However, the supposed meeting later turned out to be an ambush because as soon as Liam and his men arrived, they tried to kill Renko and Max Talia and would have succeeded except for the fact that Gibbs, Macy and Callen were present at the meeting. The three NCIS Agents used their combined firepower to kill Liam and his men while Renko protected Talia. In the aftermath of the gunfight, Agent Kensi Blye who'd helped Renko arrested Talia while Renko introduced himself to Gibbs.
Renko was later seen back at the main OSP office, listening as Kensi read out information concerning the arms dealer the OSP team had been tracking.
After Rivkin was released, Macy ordered Rivkin to tail him which Renko did, tracking Rivkin to a hotel. Gibbs later joined Renko a while with Renko heading off to go get coffee.
As Renko was returning, Gibbs received a phone call from Macy telling him that they had a FISA- (Foreign Intelligence Surveillance Court) warrant that could be used on Rivkin once he was in NCIS custody.
Almost immediately, Gibbs and Renko took separate paths with Gibbs reaching the apartment of a member of the terrorist cell and Gibbs searched the apartment for any trace, only to discover a dead body in the apartment with Renko joining Gibbs seconds later to survey the carnage Rivkin had left in his wake.
Knowing that Rivkin was seconds away, the OSP team of Sam, Kensi and Renko launched an assault on an auto-shop that their fellow agent and colleague, Callen was also in and they were ultimately successful in capturing one of the members of the terrorist cell while the other member died attempting to shoot one of the members of the OSP assault team.
Renko was last seen in the OSP office saying his goodbyes to Gibbs and McGee who were returning to Washington D.C. now that the case had been closed.
NCIS: Los Angeles Season 1Edit
In the Season 1 episode, Episode:Ambush, Renko returned to OSP, having gone on an investigation for two months on a dangerous militia group called "Enhancing Law Enforcement", also known as "ELE", which fought illegal immigration ruthlessly. Rumor had it that the ELE were going to steal the "Dragon" missiles.
After his informer, Edward Mackaye was killed by Marine Corporal Scott Reilly, Renko joined the co-operation and during the recon on Riley's vehicle, Kensi was attacked by Riley who intended to kill her by garroting her. She managed to fight back and got the upper hand in the battle before Riley escaped. Renko, who had just finished checking Riley's mail box, showed up and arrested Riley with Kensi.
Later, Renko, Kensi, and Sam tracked down the camp of ELE. After being captured by the militia, Sam contacted with Kensi via Morse code. Sam told them to use "Maskelyne" and after learning what "Maskelyne" stands for, Renko and Kensi opened fire from several locations, making the militia believe that they had been surrounded by multiple units.
In Episode:The Bank Job, Renko made an arrangement for Callen and Sam to meet Detective Matt Bernhart. The four later worked together on a fake bank robbing.
In Episode:Burned, when Callen was absent, Renko was called to rejoin the team due to the lack of personnel and possible security concerns. He joined the operation to stop Ruman Marinov and his men from killing a German CEO. Renkoe was shot during the mission but survived because of the bullet proof vest he was wearing at the time. Later, he joined the operation to catch Eugene Keelson.
NCIS: Los Angeles Season 3Edit
After being absent for most of the three seasons, Renko returned in the Season 3 finale, Episode:Sans Voir, Part 1 where it was revealed that he was working with Assistant Director Owen Granger on a case.
He was later brought to a hospital after being shot in the jaw by Marcel Janvier, and tragically suffered a fatal cardiac arrest, resulting in Renko dying which left OSP devastated. After Renko's death, the OSP team was determined to find his killer by any means necessary. Eventually they found out that Janvier was responsible and tracked him down, only to see him kill NCIS agent Lauren Hunter with a car bomb.