The Riddles were part of an important African-American family in Denison.  Agness Orviss and Minnie S. Orviss had married the Riddle brothers, John (1867-1930) and Robert J. (1875-1910).

The 1900 census showed Agnes Orviss Riddle, age 19, living with the J.H. Riddle family in Denison at 1013 W. Munson. She was listed as his sister-in-law.

John Henry Riddle (1867–1930) was a shoemaker and operated his business at at 414 W. Main; he became secretary of the Knights of Labor in Denison. His wife, Minnie S. Oviss Riddle, was "supervisor of music, penmanship, and drawing in the Denison colored pubic schools" (1901 City Directory).  That year John and Minnie were living above what would later become the Star Theater (and later the State Theater, followed by the Homestead Winery).  

According to the 1917 City Directory, John Riddle's shoe shop is located at 210 N. Rusk and his family lived at 1010 W. Munson. (Denison City Directory, 1913 - 1927)  John Riddle was secretary of the Knights of Labor in Denison and Minnie was teaching at the Anderson School.  She is also matron of the colored Order of Eastern Star.  Their son, Roscoe, was a student.  The street index for 1917 indicated that the 800 block of Munson was a mixed race block; blocks 900 through 1200 were inhabited by African-Americans.

J.H. and Minnie's son, Roscoe C. Riddle (1892–1950), graduated in 1908 from Denison's Anderson High School. He attended Bishop College, Northwestern University, and Meharry Medical School in Nashville, one of the few medical schools in America for African Americans at the time.  He served in the Army's Tennessee Medical Department during World War I.  

Dr. Riddle returned to Denison, having an upstairs office in one of the buildings on Main Street.  In 1925 Dr. Riddle founded the Sons and Daughters of Mercy Hospital to provide quality medical care for local African-Americans. Prior to his marriage he advertised in the Denison Herald for bids to be submitted for the construction of a bungalow near Mercy Hospital; John Tulloch was the architect for the bungalow.  

Dr. Riddle married Marie Antoinette Harper of Tuskegee, Alabama in 1927.  Two years later the 1929 Denison City Directory list Dr. Riddle, his wife and his parents are living at 1006 W. Munson.  His younger brother, Robert J.  and wife are living at 1024 W. Munson and Robert J. has apparently taken over his father's shoe repair business and moved the shop to 111 N. Rusk Ave.

The 1930 census listed him as hospital surgeon and his mother, Minnie, as secretary-treasurer of the hospital.  

In 1946 Dr. Riddle sold Mercy Hospital to Dr. U.C. Franklin. Roscoe Riddle and his family moved to Benton Harbor, Michigan. While there, he served as chairman of the executive committee of the NAACP.

Roscoe died in Benton Harbor, Michigan, in 1950, in another Mercy Hospital that had been founded in Benton Harbor in 1907. His body was returned to Denison for burial in Magnolia Cemetery. He and wife Marie Antoinette Harper Riddle Payne (1905–1979) named one of their two daughters after Roscoe's cousin, Gladys Riddle.

Eight months before Dr. Riddle's death, the Benton Harbor (MI) News-Palladium on Saturday, April 15, 1950, reported that he had been arrested in a gambling raid:

In a gambling raid on the swank "101" Club in Benton township, state police last night arrested 33 Negroes, including Dr. Roscoe C. Riddle, 68, 904 Pearl St., prominent Benton Harbor M.D.

Dr. Riddle, owner of the Fair Avenue building housing the club, as well as club president, was held overnight at the county jail in St. Joseph on charges of being owner of a building in which gambling was permitted. The offense, a circuit court misdemeanor, is punishable by maximum sentence of one year in county jail, $200 fine, or both.

Thomas Webb, 22, 132 Market Street, described as manager of the club, was also charged with a circuit court misdemeanor, that of operating a gambling establishment.  Conviction on the charge carries maximum sentence of two years in state's prison, $1,000 fine or both.

The 31 other persons arrested were charged with frequenting a gaming place, the charge being only a misdemeanor and punishable by fine a fine of not more than $100 and jail term of 90 days.  All 31 were given the opportunity of posting $25 bond, after being booked at the county jail, pending their appearance in justice court this morning.

Both Dr. Riddle and Webb were not allowed to free themselves by posting bonds during the night on orders of Captain C.B. Miller, commander of fifth district state police with headquarters at Paw Paw. Milller personally led last night's raid.

Dr. Riddle readily admitted to newsmen at the jail after his arrest that gambling was in progress at the club.  He claimed, however, that nothing more was "going on" than in other private clubs here and elsewhere.  Any net proceeds from the gambling, he declared, were distributed among employees of the club.

He said he did not know who owned five slot machines confiscated by the police at the club.  He said that bingo numbers, poker, dice, tank rum and [illeg] were played for money stakes regularly by club members.

State police reported they found a pool table made into a dice table, a numbers machine and other gaming paraphernalia in the club....

Dr. Riddle was in the news again on December 26, 1950, when the Benton Harbor News-Palladium carried his obituary:

Last Rites For Dr. Riddle To Be In Texas

The body of Dr. Roscoe C. Riddle, 68, prominent Benton Harbor Negro physician who died Saturday morning at Mercy Hospital, was sent via C & O Railway this morning to Denison, Texas, for burial. Funeral services will be held there Thursday afternoon.
Although Dr. Riddle had entered Mercy Hospital last Wednesday for treatment of a heart condition, his death was sudden and a shock to his family and friends.
Dr. Riddle, who was born October 27, 1892, in Thurber, Texas, had resided in Benton Harbor the past six years.  His home was at 904 Pearl Street. 
He is survived by his wife, Marle; and two daughters, Mrs. Edwin Wood, of Benton Harbor, and Miss Gladys Riddle, a student at Wellesley College, Wellesley, Massachusetts. The family also left this morning for Denison, Texas.  Dr. Riddle is also survived by his mother, Mrs. Minnie Riddle, at Denison, Texas.  His father, J.H. Riddle, preceded him in death.  The Robbins Brothers Funeral Home had charge of arrangements.