Inmate hatched castration plot after Justin Bieber didn’t return his love letters: records

He was Justin Bieber’s “Lonely Girl” — in prison. The child rapist-murderer who plotted to castrate and kill the Biebs in New York City was furious with the pop star for ignoring his jailhouse love letters, court records reveal. Dana Martin, 45, told cops he “had become infatuated” with the…