Ivanhoe Donaldson, said to be under investigation by a grand jury, is an intense, aggressive business executive and former city official whose organizational efforts in behalf of his longtime friend, Mayor Marion Barry, have helped win him a national reputation as a political strategist and tactician.

Widely known for years as the mayor's most trusted friend and political adviser, the gaunt, slightly built Donaldson managed Barry's victories in the 1978 and 1982 mayoral races and won election himself earlier this year as the District's Democratic State Committee chairman.

Donaldson, 43, headed the Department of Employment Services for part of Barry's first term, and during the second term he served as deputy mayor for economic development.

Before leaving last year to become a vice president with E.F. Hutton & Co., the brokerage and investment banking firm, Donaldson won praise from members of the business community for vigorous efforts to promote economic activity.

He was credited with helping developers and others do business in the District, with resolving major disputes with developers of two key city-owned parcels, and with spurring plans for neighborhood improvement.

A voracious reader, whose favorite authors include Dostoevski and Camus, Donaldson spurned summaries of thick government documents to digest them on his own, and he is widely known as a man of feverish energy and keen intelligence.

Beyond that, however, political observers traced his clout in city politics and government to his ties with Barry, which go back to their work in the civil rights movement in the early 1960s.

Donaldson, who was a Student Non-Violent Coordinating Committee organizer after studying electrical engineering at Michigan State University, has said he is still committed to social justice but finds government cannot eliminate poverty.

A combative man, whose hand frequently clenches into a fist as he gestures to drive home a point, Donaldson, the son of a New York City policeman, was known for whipping the administration into shape, playing troubleshooter, and being willing and able to take the heat of the political kitchen.

"When Mr. Donaldson makes a statement on behalf of the mayor, it's the final word," a City Council member once said.

When Donaldson resigned his post last year, the mayor said he "would have left earlier if I hadn't been holding onto him like glue."