A jury deliberated a few hours before finding 41-year-old Jason Bradwell Lewis guilty in the beating death last Dec. 12 of Jhordann Rust.
Deputy District Attorney Melissa Vasel said Rust and her fiance, Cory Nowell, were living a transient lifestyle and came to San Diego hoping to get a fresh start.
Once in San Diego, the couple checked into the 500 West Hotel and bought alcohol and also looked for marijuana, Vasel said.
A witness called 911 when he said he saw Nowell push Rust, and Nowell was taken off to jail, according to the prosecutor.
Rust called her mother in Wisconsin the night of Dec. 12 and said she was scared and alone. Later that night, Rust was seen with Lewis, who had been staying at the hotel.
Lewis and Rust were seen buying a bottle of wine at a nearby store, and Rust was later seen going into the defendant's fifth-floor room.
Ann Nielsen testified that her daughter called her and kept her on the phone for two hours, with two males in the background calling Rust names and saying they didn't want to hear about her boyfriend being arrested.
Rust said one of the men was cool but she was "terrified'' of the other one, according to Nielsen.
"I told her to get the hell out of there,'' Nielsen testified.
The mother said she heard a "thud'' and heard her daughter say "it hurts.''
"It kept going and going and going,'' Nielsen testified.
The mother said she called San Diego police, telling a dispatcher that her daughter was being attacked.
"Literally, someone is beating the hell out of her,'' the mother told police.
Rust's body was found later in a second-floor communal bathroom area of the hotel.
Vasel told the jury that Rust's body had been moved and dumped in the bathroom area. The prosecutor said Lewis at some point bought a large suitcase and his fingerprint was found on a sink near where the body was discovered.
Inside a nearby trash can, officers found Nowell's cell phone and a blood-stained mattress pad and some of the victim's clothing, Vasel said.
Lewis -- who has been to prison twice for battery and residential burglary -- faces 56 years to life behind bars when he is sentenced Dec. 16.