"Right now everything points to a tragic accident," Police Chief Kevin Brunelle told The Associated Press, adding investigators were awaiting forensic results.
John Tabutt, 62, told investigators he got his gun when he thought he heard an intruder, then fired at a figure in the hallway, according to Brunelle. It was Tabutt's live-in fiancee, 62-year-old Nancy Dinsmore, who family members say he was going to marry Saturday. Tabutt told authorities he thought she was next to him in bed the whole time.
A message left for a phone number listed for the house was not returned.
Brunelle said no charges have been filed against Tabutt, adding the information he provided has been verified and he appeared "very distraught."
Tabutt was "very concerned about her well-being," standing by while she was pronounced dead at the scene by paramedics, Brunelle added.
The couple planned to wed in a small ceremony Saturday at St. Stephen Catholic Church in Winter Springs, Dinsmore's son-in-law Scott Sposato, of Vero Beach, told the Orlando Sentinel.
"They loved each other," he said. "It was quite apparent."
Tabutt called 911 shortly after 2:30 a.m. Friday, moaning and sobbing, the newspaper reported.
"I thought I had an intruder in the house," he told the emergency dispatcher. "Honest to God, she looks dead."
He then thought he heard her take a breath.
"Hang in there, Honey. Hang in there," he said.
Winter Springs is about 15 miles north of Orlando.