The case was summarized in an official report by Chicago Police Cmdr. Francis Flanagan:

''On 22nd December 1967, a call was received . . . for detectives to investigate the death of one Branion, Donna, (Female/Negro) 41 yrs., the socially prominent wife of the equally prominent Branion, John M., M.D., an eminent gynecologist, who had found his wife dead of multiple gunshot wounds, in the utility room of their spacious apartment located at 5054 S. Woodlawn Avenue, 1st floor.

''The doctor related that he had left the Ida Mae Scott Hospital, where he had been treating patients, then proceeded directly to the Hyde Park Neighborhood Center, where he picked up his son, Branion, John M. III, 4 yrs. old, at 1130 hours, then proceeded immediately to his home, where he found the body of his wife.''

John Marshall Branion Jr. was the son of John Marshall Branion Sr., who was orphaned at age 13 in Mississippi but put himself through school, graduating from the University of Chicago in 1923, and then took up a 34-year public-service career as an assistant public defender of Cook County.

An only child, John Jr. fulfilled his parents` fondest dream that he become a doctor despite his poor academic record by attending medical school in Switzerland. He returned to Chicago to do his internship, set up a practice in obstetrics and gynecology and marry well. His wife was the former Donna Brown, daughter of Chicago banker Sidney Brown and a cousin of the noted jazz musician Oscar Brown Jr.. The couple had two children, a boy and a girl.

As a black physician on Chicago`s South Side, Dr. Branion should have had it made but for three weaknesses: fast money, fast horses and fancy women. He was once indicted as a member of an illegal abortion ring, getting off the hook only because a woman who was about to testify against him died before the trial. He owned race horses, which he stabled in Indiana. He took frequent ski trips to Colorado and was frequently seen in the company of ''other'' women.

All this did not go over well at home, and there was nasty talk of divorce, but the socially prominent Donna Branion did not want it.

Mrs. Branion`s sister, Joyce Tyler, was probably the last person other than the murderer to speak to her. Donna phoned her sister at 8:30 on the morning of Friday, Dec. 22, and again at 10:15 to discuss baby-sitting. A little more than an hour later, the doctor`s wife was dead.

Theresa Kentra, whose adjoining apartment shared a back porch with the Branions` posh 10-room unit on South Woodlawn Avenue, was putting away groceries at about 11:20 that morning when she heard a commotion in the Branion apartment, then a sharp report followed by three more.

Patrolman William Catizone was on routine patrol in the neighborhood when he was ordered by radio at 11:58 a.m. to meet Branion at 5054 S. Woodlawn

''regarding his wife.'' He was met by the doctor, who led him to his wife`s body on the utility-room floor. Branion told the patrolman that upon discovering his wife`s body, he ran out to the back porch and shouted ''Helen, Helen!'' to summon his physician neighbor, Dr. Helen Payne, who lived on the third floor.

''I haven`t touched her,'' Branion said. ''As soon as I observed the lividity (settling of blood) in her legs, I knew she was dead.''

Helen Payne, who was already on the scene with her brother, William Payne, identified herself to the policeman as a medical doctor, told him she had examined the victim and pronounced her dead.

By the time Detectives Michael Boyle and James McGreal got to the apartment, crime-lab people were already working the scene as Branion sat on the living-room couch, his head buried in his hands and sobbing quietly. To spare the distraught man the discomfort of having to watch the crime-lab men going about their unpleasant work while they talked to him, the detectives suggested that they go to the old Washington Park detective headquarters. Branion agreed.

Crime-lab technicians recovered three expended bullets and four cartridge casings. An autopsy later indicated 13 separate wounds-seven caused by entering and six by exiting bullets. The three slugs recovered at the scene had ripped through both her hands as she tried to fend off her attacker. One of the bullets then went through her head, another through her neck and the third into her shoulder and out her back. A fourth slug was later recovered from the body.

The detectives, meanwhile, could not get anything from Branion that might lead to the killer`s identity, and once the crime-lab crew had left, Boyle suggested continuing their talk in the apartment.

Replacing McGreal, another detective, Charles McMillan, accompanied Boyle and Branion back to the scene. After a thorough inspection of the apartment, the men concluded that nothing apparently had been taken, that there was no sign of a forced entry and that Mrs. Branion probably knew and let the killer inside herself.

As the two detectives continued to look around, Branion retired to the sun porch, where he sat sobbing into his hands. His 13-year-old daughter had come home while he was out with the detectives and was now with her younger brother and some relatives upstairs. Then one of the detectives noticed something strange: While crying his heart out, Branion was peeking through his fingers watching every move they made.

The two detectives then asked Branion if he`d mind going over everything one more time.

''Not at all,'' Branion said, stifling a sob. ''Well, like I told you before, I left my office at 11:30 this morning and drove over to pick up my son at 5480 S. Kenwood. I got there at about 11:35, and he was waiting out in front for me. Then I drove over to East 53rd Street to pick up Maxine Brown

(the ex-wife of Oscar Brown Jr.) to have lunch with us. She couldn`t make it, so we drove home. When I entered the apartment, I called out to my wife but got no answer. I sensed something was wrong. I told my boy to wait in the hall, and I went in alone. I went into the utility room and flicked on the light. I saw her lying on the floor.

''I could tell she was dead. I could see lividity in her legs. I flicked off the light, then went through the kitchen and out the back door and called for Helen Payne.''

Asked about an array of guns in the laundry room, Branion replied: ''I`m a gun collector, and I make my own ammunition. I have 25 guns-pistols, rifles and shotguns-in there.''

By then, it was 9 p.m., and the detectives decided to call it a day.

The next morning Boyle and McGreal were more than a little surprised when they discovered that Branion had taken off with his two kids for a ski vacation in Vail, Colo. ''You ask what I think?'' Boyle said. ''I think it`s time we go talk to some of the good doctor`s friends.''