Kevin Timothy Maroney, 61, a deputy assistant attorney general in the criminal division of the Justice Department who retired in 1976 with 30 years of service, died of a heart ailment Jan. 9 at Holy Cross Hospital. He lived in Silver Spring.

Mr. Maroney, who joined Justice in 1946, spent many years in the internal security division before moving to the criminal division. He represented the government in a number of important cases.

He was a leader of the government team opposing The Washington Post in the Pentagon Papers hearings, which concerned the publication of classified materials about the Vietnam War, and also was involved in the investigation of former vice president Spiro T. Agnew on charges of tax evasion and related matters.

Mr. Maroney began his career at Justice as a deputy U.S. marshal. In 1950, he became a trial attorney and in the 1950s he headed a unit in the internal security division that prosecuted cases involving communism.

By the end of that decade he was deputy chief of the criminal section in the internal security division. Later he became chief of the division's appellate section. In the late 1960s, he was made deputy assistant attorney general for internal security.

When the internal security division merged with the criminal division, Mr. Maroney was appointed deputy assistant attorney general for the criminal division. He continued that work until he retired.

After leaving the government, he was affiliated with the Washington law firm of Welch & Morgan. He retired a second time in September 1984.

In 1971, Mr. Maroney received the Justice Department's second highest honor, the Attorney General's Distinguished Service Award. He also received several bar association awards.

Mr. Maroney was born in Baltimore and reared in Washington. He was a graduate of St. John's College High School, Mount St. Mary's College and the Georgetown University law school. He served in the Navy in the Pacific in World War II.

He was a member of the St. John The Evangelist Catholic Church in Silver Spring.

Survivors include his wife, Eloise, of Silver Spring; a son, Kevin Timothy Jr., also of Silver Spring; three daughters, Patricia Madden of Bethesda, Eileen Blaustein of Silver Spring, and Katherine Spencer of Crofton, Md.; a sister, Alba Gibbs of Camp Springs, and three grandchildren.