The $15 million damage suit brought by convicted murderer Jeffrey MacDonald against the writer who chronicled the killings in the bestselling book "Fatal Vision" ended in a mistrial yesterday after it was announced that the jurors were hopelessly deadlocked.

"Fatal Vision," written by Joe McGinniss, was published in 1983 and later made into an NBC-TV mini-series. The book concluded that MacDonald had stabbed and bludgeoned his pregnant wife and two daughters to death at Fort Bragg, N.C., in February 1970. The former Green Beret captain was convicted of the killings in 1979 but still insists that drug-crazed hippies committed the murders. He is serving three life terms in federal prison.

MacDonald claimed McGinniss deceived him by posing as a friend and implying the book would vindicate him.

Authors William F. Buckley Jr. and Joseph Wambaugh testified at the trial that a MacDonald victory would inhibit nonfiction writers by instilling fear that they would be sued by book subjects who did not like the way they were portrayed.

MacDonald's lawyer said he would seek a new trial.

First Lady's Belated Birthday Party

President and Nancy Reagan will join friends and family today at their ranch in Santa Barbara for a belated birthday party for the first lady. Among the 40 persons on the guest list for the annual August celebration, organized by family friends Earle and Marion Jorgensen and William and Betty Wilson, are Ron and Doria Reagan, and Michael and Colleen Reagan and their children Cameron and Ashley Marie.

The first lady turned 66 on July 6, but in the past has given her age as 64.

Change of Scene for 'Hunter'

Stepfanie Kramer has finally drawn the line. After three seasons of going undercover (and sometimes uncovered) as Sgt. Dee Dee McCall on NBC's television series "Hunter," Kramer said yesterday that she has reached an agreement with producers that removes a planned rape scene from an upcoming three-part episode. Kramer had threatened to walk off the successful crime drama, complaining that her character was raped in the show two seasons ago.

"Basically we came to a mutual agreement as to how the story should proceed," she said by telephone from the set. "The rape has been taken out."

Executive Producer Roy Huggins originally said he would not change the plot of "City of Passion," which is based on the novel by former Los Angeles police officer Dallas Barnes.

Tower Divorce Settlement?

Former senator John Tower and his wife Lilla may have reached a settlement in their divorce case. Although neither Tower's attorney nor his wife's would confirm the settlement, the lawyers had been scheduled to appear for a hearing yesterday but jointly requested it be canceled.

Among the motions in the divorce case was a request by Lilla Tower to take depositions from at least three witnesses, including two Dallas women, whose testimony she said would "establish the expenditures and the activities" of Tower during their marriage.

Tower, 61, and his wife, 59, were married in 1977. They separated in November 1985 and filed for divorce on June 2, 1986. Tower served in the Senate from 1961 to 1985. Earlier this week, he announced he was joining a Dallas law firm to form a national and international consulting service.

The Newmans vs. the Photographers

Paul Newman and his wife Joanne Woodward ended up battling three photographers Wednesday after the three forced their way into the lobby of the Newmans' Fifth Avenue apartment building. According to free-lance photographer Barry Talesnick, Newman "just went crazy ... He said we were trespassing and cursed and shoved us. We all ducked when Joanne swung her bag at us."

Another of the photographers, Judie Burstein, claimed Newman was rough with her. Newman is unrepentant about the incident. "I couldn't have manhandled that broad with a Mack truck," he said through a publicist. "My profanity was no match for the vulgarity of the intrusion into a private building, but then I didn't have time to warm up. And I'm sorry that it helped get her name in the paper."