LOS ANGELES (AP) – Anna Nicole Smith’s partner, Howard K. Stern, was not with the former Playboy playmate when she died, but he knew she was very sick, his sister says.

Stern had told his sister that Smith was running a fever of 105 degrees shortly before her death on Thursday, and that a nurse was “icing her down” earlier that day at the Seminole Hard Rock Hotel and Casino in Hollywood, Fla.

“When he left her, she was sleeping,” Bonnie Stern said.

He had been gone only about two hours when news reached him that Smith was dead, she said. A private nurse had called 911 after finding the former model unresponsive.

Bonnie Stern, who recently traveled from her Beverly Hills home to the Bahamas to comfort her brother, said that he had tried to get Smith to visit a doctor but Smith had refused because she was afraid that it would draw publicity.

“They had plans to get a yacht and to buy an engagement ring. They were going to get married Feb. 27. It was going to be a real marriage,” she said.

Asked what she thought caused Smith’s death, Bonnie Stern said: “Her immunity was so low. She was so depressed. She kept getting sick and her body just probably broke down.”

Smith had never recovered from the loss of her 20-year-old son, Daniel, who died in the Bahamas in September while visiting his mother and newborn half-sister at a hospital, friends said. She had also spent a decade battling in court over the estate of her late husband, the 90-year-old Texas oil tycoon J. Howard Marshall II.

Alex Goen, the founder and CEO of TrimSpa, knew Smith well from working with her as a company spokesmodel and said she suffered from social anxiety, as well, even after years in the celebrity spotlight.

“She was clearly incredibly misunderstood,” Goen told CBS’s “The Early Show” on Tuesday.

Smith had met Stern in 1996 when she was referred to his law firm, Bonnie Stern said.

“He started doing her legal work and then he became her confidant. They became best friends and then he fell in love with her,” she said.

Stern, 38, is listed on a birth certificate as the father of Smith’s baby girl. He said in an interview with “Entertainment Tonight” that he is the executor of a will drafted for Smith that will leave everything to the little girl, Dannielynn Hope Marshall Stern.

Another man, Larry Birkhead, also claims to be the father, and actress Zsa Zsa Gabor’s husband, Prince Frederic von Anhalt, recently said he had a decade-long affair with Smith and might be the baby’s father. Von Anhalt said Monday that he plans to file a paternity challenge in court and wants a DNA test.

Birkhead told New York’s Daily News that he and Smith had meticulously planned for the birth of the child, but that after they broke up he was pushed to the side.

“Howard has never liked me and he never wanted me and Anna to be together,” Birkhead, 34, told the Daily News in Tuesday’s editions. “After she got pregnant, things went quickly downhill because of his difference of opinion on several matters.”

Birkhead recounted how he had tried to save Smith from her risky lifestyle. He said Smith left him because of his attempts to intervene. The couple split early last summer.

“I watched over her to make sure she was safe, and once I was basically pushed to the side,” he said, “I had no control over what she did or anyone else around her did.”

Bonnie Stern said “there were times of some intimacy” between Birkhead and Smith, but said, “Larry Birkhead was not her boyfriend.”