Frederick Knott, one of the most-produced playwrights of the last 50 years for having penned two major thrillers, Dial M for Murder and Wait Until Dark, died Dec. 17, 2002, at his Manhattan home, according to The New York Times. Mr. Knott, 86, did not write many plays — Write Me a Murder in 1961 is the only other play listed in his recent Playbill biography — but his work is regularly seen in stock, amateur, regional and touring productions around the world. His yarns were well-crafted enough to inspire famous film versions. Alfred Hitchcock directed "Dial M for Murder" (with a screenplay by Mr. Knott) starring Grace Kelly in 1954, and Audrey Hepburn starred as a blind woman terrorized by thugs in the 1967 movie of "Wait Until Dark." The latter story had a Broadway revival in 1998 starring Marisa Tomei and the antsy actor, Quentin Tarantino, as a villain.

The famous plotting twist of Dial M for Murder (1952) is that a woman is to be executed for murder and the real killer — whose alibi is airtight — must be found before time runs out. The classical actor, Maurice Evans, played the original Broadway run of the play. A British TV production of Dial M for Murder was produced before the work was seen on stage, first in London.

In Wait Until Dark (which bowed on Broadway in 1966 under the direction of Arthur Penn), the stage is famously blacked out in certain scenes so that the criminals are lost in a world that is comfortable to the tough heroine, a blind woman living in a basement apartment in Greenwich Village. An audience of the show tends to sit on the edge of the seats in those scenes — Mr, Knott and Penn knew that imagining violence was more terrifying than seeing it.

Lee Remick starred in the original Broadway run of Wait Until Dark, earning a Tony Award nomination.

Mr. Knott was born in China of English parents and earned a law degree from Cambridge University. He served in the British Army 1939-46, rising to the rank of major, and eventually moved to the United States.

Mr. Knott is survived by his wife, Ann Hillary Knott; a son, Dr. Anthony Frederick Knott; and two grandsons.