John Dickson Carr, 70, considered a master of the "locked door" murder mystery, died Sunday at his home in Greenville, S.C.

The author of more than 70 books, many of them under the pseudonyms of Carter Dickson and Carr Dickson, he created the fictional characters of Dr. Gideon Fell and Sir Henry Merrivale.

He frequently employed the technique of having the murder victim found in a room locked from the inside and them allowed his detective hero to deduce how the murderer managed to escape from a sealed room.

Born in Uniontown, Pa., he was educated at Haverford College. He lived in England from 1931 to 1948 and was considered an authority on Sir Arthur Conan Doyle, the creator of Sherlock Holmes.

During World War II, Mr. Carr worked for the British Broadcasting Co. He later lived in New York and moved to Greenville in 1965.

His books include "the Bride of Newgate," "Devil in Velvet," "Behind the Crumson Blind," "third Bullet," "The Dead Man's Knock," "Case of the Constant Suicides," "Corpse in Waxworks," "Dark of the Moon," 'Death Watch," "It Walks by Night" and "To Wake the Dead."

At one time, Mr. Carr was a writer on the Columbia Broadcasting System's "Suspense" series.

He once said that he got his plots from newspapers and books telling of old crimes or those dealing with modern criminology.

He was a former president of the Mystery Writers of America and an officer of the London Detective Club. He also belonged to the Baker Street Irregulars and London's Savage Club.

He is survived by his wife, Clarice Cleaves Carr, of the home; three daughters, Julia L. McNiven, of Mamaroneck, N.Y.; Bonita M. Cron, of New Zealand, and Mary B. Howes, of New York City, and five grandchildren.