BALTIMORE, FEB. 5 -- Maryland politicians Clarence M. Mitchell III and Michael B. Mitchell, the scions of a prominent black political family with roots in the civil rights movement, were sentenced today to 30 months in prison for accepting $50,000 to block a congressional investigation of the scandal-plagued Wedtech Corp.

U.S. District Judge Norman P. Ramsey, appearing more saddened than angry, lauded the Mitchell brothers' "great birthright" and pondered "the disgraceful displays of public corruption" by a number of public officials linked to "the shoddy operation named Wedtech."

Ramsey recounted the Mitchell family's long history in the forefront of the civil rights movement, from their mother's becoming the first black woman to graduate from the University of Maryland law school to their father's achievements as a lobbyist for the NAACP, and said, "to let this type of conduct smear the name of Mitchell is truly a tragedy."

The brothers' mother, Juanita Jackson Mitchell, alluding to the brother's claim that they were part of an FBI plot to discredit black leaders, made an impassioned plea on her sons' behalf: "We have helped this city and state become as great as they are and my sons are casualties on the road to freedom," she said.

In addition to the sentences for attempting to obstruct the congressional investigation, Ramsey sentenced former state senator Clarence Mitchell to 30 months in prison stemming from a related wire fraud charge and Michael Mitchell, who automatically lost his state Senate seat today upon sentencing, to 30 months in prison on each of two charges of wire fraud. He then ordered that the sentences run concurrently.

Ramsey also ordered Clarence Mitchell to pay $6,000 in fines and Michael Mitchell to pay $7,000. They will be eligible for parole in 10 months.

Assistant U.S. Attorney Gary Jordan, said the Mitchells had "betrayed the family legacy" and had chosen since their convictions "to wrap themselves in the mantles of martyrs" rather than show remorse. Jordan asked the judge to impose three- to four-year prison terms.

He added that the Mitchells, both Democrats, should be treated harshly because they have claimed "without one scintilla of evidence" that their indictments stem from a Reagan administration plot aimed at discrediting black politicians.

Ramsey countered by saying that he could not punish the brothers for exercising their First Amendment rights to free speech but rather sentenced them to deter "all others who may be tempted by easy money."

Paraphrasing Shakespeare, Ramsey told the Mitchells, "The fault is not in the defendants' stars, it's in themselves. They are the ones who reached out to accept dirty money."

Clarence Mitchell could have been sentenced to a maximum of 10 years in prison and Michael Mitchell 15 years for their convictions.

Meanwhile, a Baltimore grand jury today indicted Michael Mitchell on unrelated charges in connection with the theft of $77,000 from a 3-year-old boy's guardianship fund. The indictment charged Mitchell with one count each of theft, uttering and fraudulent use of a court document and alleged that the proceeds from two life insurance policies and an estate intended for the boy were used for Mitchell's benefit, the state's attorney's office said.

Additionally, a jury here last week convicted Clarence Mitchell, who served in the state legislature for 24 years, on charges of conspiracy and obstructing a grand jury investigation into his business ties to a convicted Baltimore drug dealer.

At his sentencing today, Michael Mitchell recalled serving as a plaintiff in a lawsuit his mother filed to desegregate Baltimore's public swimming pools and getting arrested at a hamburger restaurant in Annapolis that had refused to serve him because of his race.

Clarence Mitchell said, "I will pursue my ultimate vindication through all the processes available through our judicial system."

The brothers were convicted in November of attempting to stop a congressional investigation of the New York-based Wedtech Corp., conducted by their uncle, former representative Parren J. Mitchell (D-Md.), who was then chairman of the House Small Business Committee.

Wedtech, a defense firm that went bankrupt after several of its top executives were convicted on racketeering charges, has been at the center of an ever-widening scandal that has enveloped two U.S. representatives from New York, several business executives with ties to the White House, and Attorney General Edwin Meese III.

Michael Mitchell was automatically suspended without pay from the Senate today. If his conviction is upheld on appeal, he will be expelled, becoming the third state senator to have been stripped of his office for criminal activities in recent years.

The five members of the Baltimore Democratic Central Committee who represent Michael Mitchell's West Baltimore district are to nominate a replacement. The name of Del. Larry Young, the senior House member from West Baltimore, has surfaced as the likely successor, but Young said today that he had not decided whether to seek the seat.

Ramsey ordered the Mitchells to begin serving their sentences for the Wedtech convictions in 60 days.