A post-mortem on Amanda Strous revealed she suffered significant burns and was subjected to blunt force injuries before she died on June 18.
The 27-year-old, from Charlotte, North Carolina, in the US, was found with only a pair of bikini bottoms on and her mouth covered with duct tape.
Her neighbour, Matthew Thomas Benner, has been charged with her murder and first-degree arson.
Authorities believe the 28-year-old, who lived in the same apartment complex, had been stalking Strous.
The autopsy was carried out by Mecklenburg County Medical Examiners Office, and investigators are also looking at the results of a rape kit to determine if she was also sexually assaulted before her death.
According to WSOC-TV, released search warrants suggest Benner had expressed interest in dating Strous and a friend of hers.
Benner fled Charlotte after she was killed, but confessed to her murder two days later when he was arrested near Las Vegas.
Witnesses had seen him outside the apartment on the night of the killing with blood on his hands.
Strous was working as a college counselor at Central Piedmont Community College, and was set to marry to her fiancé, Cory McCleaf, at the end of last month.
Her partner had been on his stag weekend when she was killed.
McCleaf said he was devastated by his fiancee's death.
He told the Charlotte Observer: "She lit up a room when she walked in.
"Her smile was just one of those things that people had to be with.
"When she smiled they smiled.
"She was the light of my world.
"She was one of the most positive people I've ever been around."
Neighbours alerted emergency services on the night of Strous's murder after seeing smoke coming from her apartment.
They said they heard a chilling scream before the smoke alarm went off.
Her mother, Crystal said: "It's a parent's worst nightmare.
"You never think it's going to happen to you."
Her father, Eric, speaking to Channel 9, said: "I would tell you I'm broken, shattered, but as (my wife) said, love hope and faith are the foundational properties that we have raised our children to young adults that are productive in giving back."