The jury in the criminal conspiracy trial of tobacco heir Smith Bagley and four others retired at 7 tonight without reaching a verdict.

The jury will resume deliberations in the morning, and foreman Sandford W. Turner said in a note to the Judge, "We plan to . . .reach a decision tommorrow."

The panel of eight men and four women began their deliberations at 3:20 p.m. today after listening to a 95-minute charge by U.S. District Court Judge Robert Merhige Jr.

At 4:05 p.m., the jury returned briefly to the courtroom after foreman Turner sent a note to Judge Merhige requesting that he repeat his instructions made by the government.

"What elements need to be present?" the foreman asked in his note to the judge.

The government has alleged that the five defendants conspired to manipulate the stock of Washington Group Inc. and to misapply bank funds.

The judge told the jurors that under the first count of the criminal indictment brought against the defendants, they must determine that both manipulation of the stock and misapplication of bank funds be present for any of the defendants to be found guilty of a conspiracy.

Its indictment, the government alleges that between Feb. 1, 1974, and April 15, 1975, Bagley and the four others conspired to arranger loans at the Winston-Salem branch of the Northwestern Bank in order to finance the manipulation of the stock of the Washington Group. Bagley was president, and another defendant, James Gilley, was chief financial officer of the one-time Winston-Salem textile and food conglomerate which went bankrupt in June 1977.

The second count of the indictment charges the defendants individually with manipulating the stock of the Washington Group.

Besides Gilley and Bagley, the other named defendants are William F. Thomas, a prominent stock broker in Winston-Salem; Dewey W. Chapple, a former vice president of Northwestern Bank; and Shirley Grubb, who was administrative assistant to Bagley. CAPTION: Picture, Smith Bagley and former secretary Shirley Grubb sprint across street in Richmond to avoid photographers in early days of trial. UPI