Arnold Sagalyn, former journalist and federal law enforcement official. ( Louise Sagalyn / Louise Sagalyn )

Arnold Sagalyn, a onetime assistant to crime-fighter Eliot Ness, who later used his positions in federal law enforcement to advocate for nonlethal police practices and a centralized call system, which led to the creation of the 911 emergency number, died Sept. 11 at his home in Washington. He was 99.

His wife, Louise Sagalyn, confirmed the death but did not provide a specific cause.

After stints in journalism, law enforcement and business, Mr. Sagalyn was named director of the Treasury Department’s Office of Law Enforcement Coordination in 1961. In that position, he directed Treasury enforcement policies in the Coast Guard, Internal Revenue Service, Secret Service and the former Bureau of Narcotics and Bureau of Customs.

He served as the U.S. representative to Interpol, the international policing agency, and later had a staff position with the National Advisory Commission on Civil Disorders, also known as the Kerner Commission for its chairman, Gov. Otto Kerner (D-Ill.). Among other things, the panel examined the cause of riots that had engulfed cities such as Los Angeles, Chicago and Detroit in the 1960s.

In March 1968, the commission issued a report about the root causes of urban crime, notably institutional racism and poverty, and concluded that the country “is moving toward two societies, one black, one white — separate and unequal.” The report, which recommended neighborhood-building and civil rights initiatives, became a best-selling volume in paperback, but its impact was blunted by a new set of riots after the assassination of the Rev. Martin Luther King Jr. on April 4.

Throughout the 1960s, Mr. Sagalyn became known for speaking and writing nationally in support of nonlethal force in police procedures. He advocated for the use of mace or other debilitating spray propellants to immobilize suspects and the use of paint pellets fired from guns to identify fleeing suspects and getaway cars.

He also helped draw up recommendations for a nationwide emergency response number, using his frustrating experience of “waiting up to 75 rings without an operator responding,” as he wrote in an unpublished memoir.

Mr. Sagalyn included his findings in letters to the Federal Communications Commission, which spurred action ultimately leading to the establishment of the 911 emergency calling system.

Arnold Sagalyn was born March 2, 1918, in Springfield, Mass., where his father was a businessman. He graduated in 1939 from Oberlin College in Ohio, then went to work in Cleveland for Ness, who was the city’s director of public safety at the time.

Ness had previously been a U.S. Treasury agent who helped bring down Al Capone and other crime lords during the Prohibition era and who was portrayed by Robert Stack on the hit 1959-63 television show “The Untouchables” and later by Kevin Costner in a 1987 film version.

Mr. Sagalyn first came to Washington in 1942 to organize a national law enforcement effort to curtail prostitution. Later, he served as an Army officer, helping to reestablish civilian order in Germany after World War II. From 1947 to 1954, he held reporting and editing jobs with Life magazine, the New York Times and NBC News.

He then spent three years in the lumber business in Oregon before returning to the Washington area in 1957 as a part-owner and editorial page editor of the Northern Virginia Sun, a daily newspaper based in Arlington. He left the money-losing paper in 1961 to take the law enforcement job at Treasury.

In the 1970s, he was a staff member of a House of Representatives panel investigating the possible impeachment of President Richard M. Nixon. Mr. Sagalyn operated a consulting firm, Security Planning Corp., from 1970 until his retirement in 1990.

Survivors include his wife of 59 years, the former Louise Edelman London of Washington, and their daughter, Lisbeth Stone of Chicago. Mr. Sagalyn adopted his wife’s three daughters, Laurie Sagalyn of New York City, Rita London of Brooklyn and Dana Sagalyn, who died in 1986. Other survivors include three grandchildren.