Paula Sladewski, 26, who appeared in Playboy magazine and the 2003 movie, "Playboy: The Ultimate Playmate Search," was in Miami for a weekend of partying and celebration with her live-in boyfriend, Kevin Klym, police told ABC News.
Klym and Sladewski lived together in Michigan and California.
The relationship between the couple was "loving and volatile," Klym's lawyer, Marc Beginin, told ABC News. He added that his client is "totally devastated over this situation."
Sladewski's body was discovered Sunday -- but because of extensive burns, her remains were not identified until Wednesday. North Miami police used dental records to positively identify her.
Sladewski was last seen alive at 7 a.m. Sunday at Club Space in Miami.
Klym told police that he and Sladewski were separated at the club after they got into a drunken argument and Klym was asked to leave by club bouncers.
"He requested the bouncers communicate with her to say that he was waiting outside and the bouncers said they did that," Beginin told ABC News. "They came out and said she didn't want to leave, she wanted to stay."
Klym went back to their hotel and waited for his girlfriend, who never returned.
That night, hours later, Sladewski's body was discovered by Miami Dade firefighters who were responding to reports of a fire in a dumpster behind a propane store.
The body, which was still burning, was beyond recognition.
As North Miami Police attempted to identify the body, Klym first called Miami police and "a squad car came to the hotel to take the missing person's report," Beginin said.
On Monday, Klym called Sladewski's family in Michigan to tell them she was missing. He eventually hired a private investigator and canvassed South Beach with flyers.
"He was calling police stations, jails and hospitals," Beginin told ABC News.
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The model's boyfriend has not been charged in connection with Sladewski's death, but North Miami police Lt. Neal Cuevas said Klym is a "person of interest" because he was one of the last people to see her alive.
Sladewski's sister, Kelly Farris, travelled to Florida to help identify the body and told reporters at a press conference Wednesday night that her sister "loved life, she was full of life."
"I didn't imagine anything like this happening," Farris said.
Because of the extent of the burns, Sladewski's sister said, "we can't even give her an open casket, we can't even see her again"
Farris, appearing with North Miami's mayor and police chief, asked for anyone with information into the death of her sister to come forward.
"I can't see myself going back to work, and I can't see myself living a normal life until I know whoever did this pays for it," she said.
Sladewski's parents did not immediately respond to phone calls from ABCNews.com for comment on the case.