Rako Hardeen was once a member of the mercenary group known as Marvasa's Marauders in the Cyrillian Protectorate.
During the Clone Wars, Hardeen was hired to murder Jedi Master Obi-Wan Kenobi by shooting at him from the top of a building on Coruscant by an anonymous client, actually members of the Jedi High Council. After shooting Kenobi, Hardeen was pursued by Anakin Skywalker. The bounty hunter escape using a speeder bike.
While celebrating his high-profile kill, he was summoned into the back room to meet his employer and was met by Jedi Masters Mace Windu and Obi-Wan Kenobi his supposed victim, now physically altered to look like him. Hardeen was apprehended by the two Jedi, and his identity assumed by Kenobi in order to plant himself in the Republic Judiciary Central Detention Center.
Hardeen's reputation for having killed a Jedi was essential to the plan, as Kenobi used it to gain the trust of other prisoners and attract the attention of Moralo Eval, from whom Kenobi was to acquire intel that would help the Jedi prevent the assassination attempt.
Rako Hardeen is aloof, edgy, cool and tries to avoid getting in trouble but he will fight if he has to. Hardeen tends to be calm most of the time but does not like being pushed around.