The project focuses on a young couple who do not realise they are living next door to a murderer, The Wrap reports.
Mehlman explained that he was inspired to write the project when the mobster Whitey Bulger was discovered in Santa Monica after years of searching.
"I can't imagine how many times I walked past him," Mehlman said. "They had a dog and walked it in Palisades Park. I walked [my dog] Izzy there every night at sunset. I probably saw him 50 times - and he has 19 murders under his belt allegedly."
Mehlman also revealed that he would love John Malkovich to play the criminal in his potential Fox comedy.
Mehlman is best known for his work on Seinfeld but his credits also include shows like It's Like, You Know and Father of the Pride.
Fox is currently developing a number of new projects, including a sitcom from Cougar Town and Scrubs creator Bill Lawrence, a teen drama from the creator of Greek, and Tyler Labine's comedy Guidance.