Erik and Lyle Menendez are experiencing newfound fame behind bars thanks to the popular Netflix series about the gruesome murders of their parents ... and there's a weird request that keeps coming up in the fan mail that's been pouring in, TMZ has learned.
A source with knowledge at Richard J. Donovan Correctional Facility in San Diego tells TMZ ... the infamous brothers have seen a "huge" increase in mail from fans (and, of course, some haters) thanks to wild interest in Netflix's "Monsters: The Lyle and Erik Menendez Story.