Why is Ilya Koslov pretending to be Reddington?

Ilya Koslov took Raymond Reddington’s place following his death, changing his face with extensive plastic surgery.

Ilya Koslov pretended to be Raymond Reddington in order to gain access to the money the crime Cabal placed in his name to frame him for treason.

The show “The Blacklist follows Raymond “Red” Reddington (played by James Spader), a former U.S. Navy officer turned high-profile criminal who voluntarily surrenders to the FBI after eluding capture for decades.

Elizabeth Keen, a rookie FBI special agent and criminal profiler has her entire life uprooted as Raymond Reddington insists on speaking only to her.

Elizabeth Keen is picked up by the FBI and driven to a black site to meet Reddington who tells the FBI that he has a list of the most dangerous criminals in the world that he has compiled over his criminal career called the “Blacklist” and offers to help the FBI track down and apprehend them in exchange for immunity from prosecution.