Davros

Davros was an assassin for an elite Russian criminal cartel, Red Square, during Day 8. He was the trigger-man for the plot to kill President Omar Hassan and had a cover identity of Mike Farmer, a NYPD officer.

Before Day 8
Farhad Hassan, brother of Omar Hassan, President of the Islamic Republic of Kamistan, was conspiring to have him back out of a peace treaty with the United States. To help him with this mission, he had contacted some Russian terrorists, namely Davros. Together they conspired to have President Hassan killed.

To achieve this, Davros built a cover for himself as a New York Police Department officer by the name of Mike Farmer. His intention was to be part of the security detail at the United Nations the day of the peace treaty signing.

Shortly before Day 8, Davros had been in contact with the nuclear weapons that Farhad had planned to buy. This had left traces of Uranium-235 on his body. At some point, Davros also managed to break into Meredith Reed's apartment while she wasn't there. During the brief time he was there, he managed to hack into the UN servers from her computer and planted incriminating evidence to frame her.

Davros was also heading the hits against Victor Aruz, Manuel Escobar, and Mauricio Teyes, which the Russians had hired to get him inside the country. Davros and his men managed to kill Escobar and Teyes shortly before Day 8.

Day 8
While looking for Victor Aruz, Davros was in a hideout monitoring emergency channels. At around 4:28pm, he heard an officer inform about finding Aruz' vehicle, and he sent his spotter and sniper to get rid of him.

Not wanting things to go wrong, Davros went out on his own and found out that his men had failed on intercepting Aruz. Shortly before 5:00pm, he fired a Stinger missile from a rooftop near West 21st, killing Victor Aruz and at two other CTU agents. He then called Farhad Hassan to confirm that all he and his men needed was an hour until the attack.

Under the cover of his alias, he showed up to the house of police officer Jim Koernig and his wife Maggie to ask for them to change shifts, so Davros could be closer to the press-conference to assassinate President Hassan. When Jim unexpectedly refused, Davros dropped his cover identity and held both of them at gunpoint. He shot Maggie in the thigh to prove he wasn't going to back down and demanded Jim call up their commanding officer to ask for the change in shifts. After Ravello agreed to swap Jim's shift at the United Nations with "Mike Farmer", Davros executed both Jim and his wife by gunshots to the head.

He then went to the United Nations building where he met fellow officer Rabinowitz, who asked him about Jim. After telling him that Jim had fallen ill, he and all NYPD officers met with CTU Director of Field Operations Cole Ortiz to ultimate security details about the peace treaty signing. He then headed out to take his post on the street. When Farhad called him to inform him that his brother had confessed the relationship with Meredith Reed, which would probably blow their cover, Davros told him that the plans were still going ahead.

When CTU discovered schematics for an alleged bomb at the United Nations on Meredith Reed's computer, they ordered the evacuation of the building. Stationed on a nearby street, Davros activated a bomb hidden in a manhole intending to blow it up when Hassan's car passed over it. After Hassan boarded his car, Farhad called Davros and told him Hassan's car was the third one. However, Jack Bauer informed Cole Ortiz of the fake threat and Ortiz managed to swerve in front of Hassan's car protecting him from the explosion.

Following the explosion, Davros approached the car gun in hand, intending to shoot Hassan but he relented and tried to walk away. While trying to escape, Ortiz recognized him on the street and Davros fled into an office-building down the street. Inside he was called by Farhad who asked what went wrong. Davros told him that the operation was blown and to flee before they figure out he was the mole. In the south-west corner of the building, he captured Ortiz at gunpoint and forced him to his knees. He ordered Ortiz to call CTU to clear a side of the building so he could escape.

Ortiz called CTU but rather than do what Davros ordered of him, he revealed to CTU that Davros was with him. As he prepared to execute Ortiz, Davros was suddenly shot twice by Jack who had entered the room. Davros fell down dead and Jack ripped open Davros's shirt, which revealed Red Square gang tatoos all over his chest. Jack took pictures of the tattoos with his cell phone and sent them to CTU.

Ortiz then took Davro's corpse to CTU Forensics where he was autopsied by Dr. Laura Hendricks. As she was beginning to do so, the radiation alarm went off revealing that Davros had, at some point very shortly before his death, been in contact with weapons-grade uranium. This revealed to Omar Hassan that his brother, Farhad Hassan, was very close to purchasing illegal uranium rods from Red Square.