JACKSON, Miss., Jan. 11--Justice Department cloaked witnesses in secrecy today as the government offered a federal grand jury evidence in the slaying of three civil rights workers last June.

John Doar, head of the department's civil rights division, issued a terse "no comment" during the proceedings.

U.S. marshals kept spectators from seeing who entered and left the grand jury room. The witness room likewise was out of sight. Witnesses were escorted into the federal courthouse by a back door early in the morning.

U.S. District Judge Harold Cox told the jurors when they convened today they should be able to wind up work.

This marked the government's second by Friday.

second attempt to get the grand jury to return indictments.

The 23-member grand jury, which includes a Negro woman, considered the case last October but returned no indictments.

He said that despite gains in weaning people away from cigarette smoking, the habit still kills at least 125,000 Americans annually-and may even kill as many as 300,000.

Terry said that "measurable, discernible" progress made during the past year in getting additional people to swear off cigarette smoking brings to some 18 million the number of Americans who are now "ex-smokers."