The Nostrand Avenue building where Sergeny Mamontov chopped up his roommate, Aleksandr Zilbergleyt. Source: Google MapsSergey Mamontov, the 50-year-old lunatic who brutally butchered his 55-year-old roommate Aleksandr Zilbergleyt received a 25 years to life sentence on Monday. The New York Daily News reported that Mamontov’s case horrified jurors and