A Florida man is facing a murder charge after he admitted fatally stabbing his female roommate as she was saying goodbye to him, police say.

Brooke Preston, 21, visited the West Palm Beach home on Friday night to pick up a few items after moving out.

Randy Herman, 24, allegedly gave her a T-shirt and one last hug before he began stabbing her repeatedly.

Ms Preston was planning to move back to Pennsylvania to be with her boyfriend, local media report.

Her friends said she was not romantically involved with her alleged attacker, about whom she had expressed concerns.

Ms Preston was at the property on the eve of her death, but had left because her roommate’s behaviour made her uncomfortable, reports WPTV, a Palm Beach news station.

She returned on Saturday morning to collect her belongings when the accused attacked her, say investigators.

Police say the suspect phoned authorities to report the killing after driving the victim’s car to a nearby park.

During the call he confessed to the crime, according to police.

“Someone’s been murdered,” a tearful Mr Herman told the emergency dispatcher, according to the Palm Beach Post.

“Just send the police. It was me. I’m sorry.”

Police said the suspect was covered in blood and had a cut on his hand when they arrested him.

Ms Preston was found inside the house with a dozen fatal knife wounds to her back, throat and abdomen, as well as defensive injuries to her left hand.

She and the suspect had attended the same Pennsylvania high school before ending up in the south Florida apartment share.

In February 2015, the suspect’s father was accused of killing his girlfriend in Pennsylvania, but took his own life before he could be arrested.