After a night of singing karaoke with friends, 21-year-old Rosemary Flynn went to sleep in the Canyon Country apartment she shared with her boyfriend.

Her family still doesn’t know why she didn’t wake up. Flynn died in her sleep on July 31.

“I do need to find out exactly what happened,” said her father, Matt Flynn, on Monday. “But it doesn’t really matter to me what it was. It may help. I miss her a lot.”

Rosemary may have bumped her head before going to sleep, her father said, but the coroner has not yet determined a cause of death. Flynn said his daughter was in good health and ran track, played softball and basketball at Canyon High School.

Rosemary was weeks away from applying for her state license in phlebotomy — the process of collecting blood samples — and was looking forward to spending time with her extended family in Italy.

About 125 of Rosemary’s friends and family members went to a candlelight vigil Aug. 8 in Canyon Country Park to remember her. 

“Rosemary was always coming to the aid of her friends,” Flynn said. “She was very outgoing and had a big heart. That’s why there were so many people there.”

When Rosemary was born, she nearly died three times in the hospital’s intensive care unit when her lungs filled with fluid, he said.

“We feel lucky to have the 21 years. We did almost lose her three times, and I remember that being the worst day of my life until this happened,” Flynn said. “It’s nice that she affected so many people in a positive way.”

Rosemary is survived by her parents, Matt and Lucia Flynn; brother James Flynn, 19; grandmother Rosemary Flynn; and several aunts, uncles and cousins.