A 12-gauge shotgun allegedly used to murder one man and wound three others at the District Building last March was exhibited in court yesterday at the trial of 12 Hanafi Muslims on charges of murder, kidnaping and conspiracy.

The shotgun was part of a display of weapons seized at the District Building following a takeover there that lasted from March 9 to March 11. Included were three machetes, two straight razors, 32 12-gauge shotgun shells loaded with double-0 buckshot, several knives and a curved and decorated sword with a brass and red plush sheath.

Officer Boyd M. Talley testified that he had found a shotgun pellet in the clothing of Maurice Williams, 24, a reporter for radio station WHUR. Williams was killed by a blast of double-0 buckshot in the opening minutes of the siege at the District Building, where 15 hostages were taken.

Otto Williams, the dead man's father, took the witness stand to attest that he had gone to the D.C. medical examiner's office the day after the shooting to identify his son's body.

These were among the highlights as the trial of the Hanafis drew to the close of its fifth week. All 12 defendants are charged with the murder of Williams, although only two of them were presented at the District Building.

The others allegedly took part in almost simultaneous takeovers of the international headquarters of B'nai B'rith, the Jewish service organization, at 1640 Rhode Island Ave. NW. and at the Islamic Center, 2551 Massachusetts Ave. NW.

The prosecution has charged that the three sieges were part of a conspiracy to compel officials to turn over five Black Muslims convicted of murdering seven members of the family of Hamaas Abdul Khaaiis, 55, alleged leader of the Hanafis, for purposes of revenge.

Yesterday's session was marked by a number of sharp exchanges between Superior Court Judge Nicholas S. Nunzio and defense and government attorneys.

Stephen J. O'Brien, the attorney for Abdul Al Qawee, 22, also known as Samuel Young, asked Nunzio to instruct the jury that the case in which the weapons were displayed was different from similar cases in which weapons seized at the Islamic Center and the B'nai B'rith building were displayed. Al Qawee is accused of taking part in the Islamic Center seizure.

Nunzio denied the request and termed it "ludicrous."

At another point, Nunzio gave pointed advice to Assistant U.S. Attorney Martin J. Linsky, one of the two prosecutors, and to Harry T. Alexander, a former Superior Court judge who is defending Khaalis.

Alexander was cross examining Officer William L. Rull of the Metropolitan Police mobile crime laboratory. Rull, the day's main witness, was testifying about the "chain of custody" through which the exhibits had passed. The purpose of this testimony is to establish whether any of the exhibits could have been tampered with from the time they were seized until they were presented in court.

When Alexander began to ask about material the government had not introduced.Judge Nunzio asked Linsky if he wished to object. A rule of evidence limits cross-examination to subjects brought out on direct examination.

Linsky said he had no objection to Alexander's questions. Nunzio then directed that the material be produced in court and ordered a recess.

At the close of the recess, Linsky said the exhibits were locked up.

"I suggest, sir, that if you want to grant gratuities you should have the material present and be prepared to make it available," Nunzio said.

He turned then to Alexander.

"This whole line of questioning is immaterial," he said. "If you want to bring it on (in evidence), it's preserved, sir. But this is (the government's) case, not yours."

The prosecution is expected to finish putting on its case by the end of next week.

Its evidence has been massive. Yesterday's display included the double doors leading to the City Council offices where hostages were held at the District Building through which shots were fired. It also included the ornamental sword, said to be the property of City Council Chairman Sterling Tucker, who was not present at the siege.