BALTIMORE, NOV. 4 -- The defense of Maryland politicians Clarence and Michael Mitchell rested abruptly today with neither brother taking the stand to answer charges that they schemed to block an investigation of the Wedtech Corp. by their congressman uncle.

In a calculated gamble that one attorney described as a "tough choice," the defense decided to forgo testimony by the influential political figures. The decision came as their uncle, former representative Parren J. Mitchell, vigorously denied in federal court that either of his nephews spoke to him -- much less pressured him -- to stop an inquiry into Wedtech's status as a minority-owned firm in 1984 and 1985 by the House Small Business Committee. That committee was then headed by Parren Mitchell.

Parren Mitchell is not a defendant in the case and has been described by Maryland's chief federal prosecutor Breckinridge L. Willcox as an "innocent victim" of his nephews.

The case is expected to go to the jury late Thursday after prosecutors and defense attorneys present final arguments and U.S. District Judge Norman P. Ramsey instructs the panel on federal conspiracy laws and related statutes.

The defense decision to forgo testimony by Clarence and Michael Mitchell was a matter of "trial strategy," said defense attorney David R. Mellincoff. It involves a dilemma faced daily by trial lawyers: Should a defendant take the witness stand and give his side of the story but face possible damaging cross-examination by prosecutors? Or should he remain silent but incur suspicion by the jury that he is hiding something, even though the judge instructs the jury that it should infer nothing from a defendant's silence.

The Mitchells and their six lawyers huddled several times today during trial intermissions. At one point, they met for 20 minutes in a courthouse library with Clarence and Michael Mitchell's mother, Juanita Jackson Mitchell, civil rights activist and lawyer who has been attending the trial since it started.

Attorneys would not detail their decision to keep the Mitchells silent. Attorney Abbe D. Lowell said only that "the important words in this case, either spoken or unspoken, were by the government's witnesses," a reference to defense claims that prosecution witnesses failed to show any attempt by the Mitchells to "corruptly endeavor" to stop their uncle's investigation.

Former Wedtech officials have testified they paid the Mitchells $60,000 to stop the investigation.

The officials said the Mitchell brothers pledged to get the investigation stopped without specifying how. Defense attorneys contend the prosecution has failed to show the Mitchells intended to "corruptly" stop the probe by bribing, coercing or intimidating their uncle.

Parren Mitchell, 65, testified today that he began the investigation after receiving numerous tips of improper activity by various political operatives, including Lyn Nofziger, a former White House adviser now under indictment on charges of violating federal ethics laws and lobbying illegally for several clients, including Wedtech.

Parren Mitchell said he was never approached by his nephews about Wedtech, despite the fact that they saw each other here in Baltimore "almost all the time."

When the Small Business Administration gave Wedtech a "clean bill of health," he said, he set the investigation aside. Prosecution witnesses alleged earlier that an SBA letter clearing Wedtech was concocted by an SBA official on Wedtech's payroll.