On a perfect summer day Theartice (Butch) Boyd drove his sister Brenda Denise Boyd, his mother, his sister's best friend and her mother to Baltimore-Washington International Airport in a white limousine.

The women were headed for Butch Boyd's condominium on Paradise Island in the Bahamas, and they were ecstatic. It was a dream come true for Butch's sister, called Denise by friends and family.

It was her first visit to the condo, but more important to her, she had saved enough money to take her 65-year-old mother. She left her 10-month-old son with a sister; it was a women's vacation.

"They were so happy. I didn't know what I was taking them to," Boyd said in retrospect, sitting in the kitchen of his Arlington home yesterday.

On June 24, 1985, two days after Boyd dropped the women at the airport, Denise Boyd, 25, a Piedmont Airlines reservationist who lived in the District, was dead. An autopsy concluded she died of "asphyxia as a result of drowning," but also said, "her body showed numerous injuries such as bruises to the back, forehead, mouth, nose and inside elbow." A Bahamian man, whom the two young women had known briefly, has been charged with murder.

The Bahamian government and its judicial system, Boyd said, have given the family little information regarding the trial of the man accused of murdering his sister. And, he said, the State Department has been slow in assisting the family.

"We've had to do all of the leg work, the expenses," said Boyd, who owns a limousine service.

Yesterday Boyd received a Mailgram from the American Embassy in Nassau, the first time the family received official notice of a court date. The letter was prompted by a series of calls to the State Department, said Boyd.

"I found out about the preliminary inquiry just three days before they held it," he said. "No one contacted the family. If I hadn't called a friend there, we never would have known."

Next, he called the Bahamian police, who confirmed the date, Boyd said, and told him that he, his mother and the two other women who had accompanied his sister on the trip would be reimbursed for expenses if they came to Nassau for the hearing. They all attended the Sept. 5 hearing and the women testified.

"We're still waiting on our $1,500 reimbursement," said Boyd. "It's a small thing compared to my sister's death, but it's the principle and their attitude about this whole ordeal."

There was no one at the State Department who could discuss the specifics of the Boyd case yesterday, but Anita Stockman, a press officer, said, "Judicial systems vary and may be strange to us, but we can only work according to the laws of that country.

"It can be difficult and frustrating getting information. The State Department notifies the embassy, which notifies the foreign ministry of the host country . . . . " Answers travel the reverse route back. "Sometimes the information isn't available until the 11th hours," said Stockman.

Boyd is grateful his sister's best friend was with her on the trip, or he believes he would have never known the circumstances surrounding her death.

"They went out to dinner and ran into these two guys they had met earlier in the lobby," said Boyd. "One of them is the brother of a friend of mine.

"I can't remember if Denise had ever met him before, but she knows of him so I'm sure she felt safe with him," he said. "Anyway, these guys asked them if they would like to go for an early-morning boat ride. Before Denise left she told me she wanted to get pictures of the morning sunrise.

"She probably jumped at the opportunity. They went to a little island about 15 minutes from Paradise. The four of them went for a swim. When they got out of the water, the couples walked in separate directions. I guess the women didn't think anything would go down.

"When Michelle got back she and her friend called Denise, but they didn't get an answer. They went to the boat to wait. When it got lighter they saw her sprawled out on the beach. He was standing over her. He had a busted lip and some scratches on him. They put her in the boat and took her to the hospital."

Denise Boyd was pronounced dead at the hospital. "The police determined there was a struggle," said Boyd. "Denise was so much like me, very, very friendly, outgoing, always laughing and joking. I think this guy got the wrong impression about her."

The trial for the man accused of murdering Denise Boyd is set to go before the Supreme Court of Justice in the Bahamas, according to the Mailgram. The case probably will not be ready for the January 1986 session, and the next session would begin in April, the letter said.

Butch Boyd, his mother and the other two women will journey to the island again for the trial. "This could happen to anyone," said Boyd. "We are luckier than some people. What would have happened . . . if we hadn't had the money to go down there on our own?"