Nelson M. "Nick" Oneglia, 52, a College Park lawyer who lectured extensively on domestic relations and child custody law, died Dec. 10 at Georgetown Hospital. He had multiple sclerosis.

Mr. Oneglia, who lived in Washington, had appeared on local television and radio shows as an expert on family law and frequently conducted training seminars for other lawyers and for social workers.

He was a native of the Bronx in New York and a graduate of the University of Maryland and its law school. He had lived in this area since 1965.

As a specialist in domestic relations, Mr. Oneglia was the prevailing lawyer in several landmark cases that established legal principles in family law in Maryland and the District.

One case before the Maryland Court of Appeals established the principle that pensions are to be considered marital property in divorce cases.

Another case before the D.C. Court of Appeals established the principle that one spouse could not be ordered to sign a joint income tax return.

Mr. Oneglia was managing partner of the law firm of Horowitz, Oneglia, Goldstein, Foran and Parker in College Park from 1977 to 1986, then established his own practice. He had served as legal counsel for the Hospital Commission of Prince George's County.

Mr. Oneglia served in the Army from 1957 to 1963 as a military police officer in Germany and was a private investigator in Miami from 1963 to 1967.

He taught from 1976 to 1988 at the University of Maryland, where he organized a legal internship seminar for undergraduates. He also was a consultant to the Army, presenting training and seminars for military personnel throughout this country and Europe on equal opportunity matters and criminal and family law problems encountered in the armed forces.

Mr. Oneglia was commissioner and legislative leader of the Montgomery County Commission for Women from 1982 to 1984. In that capacity, he conducted training sessions on sexual harassment for the county police department.

His marriages to Angelina Trujillo and Stewart Oneglia ended in divorce.

Survivors include his wife, Susan Russell of Washington; a son from his first marriage, Nelson M. Oneglia Jr. of Oxnard, Calif.; three stepchildren from his second marriage, Larkin Preston of Atlanta, Richard K. Preston II of Chevy Chase and Bannon Preston of Bethesda; a brother, Mario Oneglia of Montclair, N.J.; a sister, Rosemary Langemann of New Orleans; and four step-grandchildren.