BOSTON -- Investigators continue to sift through clues in the slaying of a Boston graduate student who was found dead in a vacant lot in New York City last weekend.

NewsCenter 5's Amalia Barreda reported that a transcript of Imette St. Guillen's last known phone conversation was released Wednesday by the New York Post.

St. Guillen, 24, was found nude, strangled and suffocated Saturday after a friend, Claire Higgins, left her alone at a bar at about 2:30 a.m. Saturday.

Surveillance video shows St. Guillen arguing with her friend around 3 a.m. Saturday outside the Pioneer bar in the Bowery because St. Guillen wanted to stay and her friend, West Roxbury native Higgins, wanted to go home. Higgins waves goodbye and then leaves in a cab while St. Guillen heads back into the bar alone. About 30 minutes later, Higgins called St. Guillen on St. Guillen's cell phone and St. Guillen said she had moved to another bar in the same neighborhood.

"Where are you?" Higgins asked.

"I'm in another bar," St. Gullien said.

"When are you going home?" Higgins asked.

"Later. I'll be home later," St. Guillen said.

Police found St. Guillen's body in a vacant lot in Brooklyn's East New York section Saturday night. Her ankles were bound with shoelaces, her head wrapped in packing tape. She had been sexually assaulted. Police released pictures of a flower print bedspread in which St. Guillen's corpse was wrapped. They said the bedspread similar to the kind used by some inexpensive motels.

Detectives are also trying to identify the man who called police on 911 from a Brooklyn diner, tipping them off about the body in the vacant lot.

St. Guillen's mother, Maureen, and her sister, Alejandra, appeared on MSNBC Tuesday night, pleading with anyone who has information to come forward.

"We're just hoping that someone out there says something, if they saw anything, or if they know anything, just the smallest detail, she just ... you know, nobody deserves this," Alejandra St. Guillen said.

St. Guillen was scheduled to graduate this semester from John Jay College of Criminal Justice in Manhattan. She attended George Washington University as an undergraduate and graduated magna cum laude. She graduated from Boston Latin high school in 1999.

The family and Boston Latin are working to create a scholarship in St. Guillen's name.

St. Guillen would have turned 25 on Thursday.