Hayward --

A Union City woman was charged with murder Thursday in the slaying of a nursing student who vanished from a Hayward parking garage more than three months ago.

Giselle Esteban, 27, who is pregnant, was scheduled to appear at the Hayward Hall of Justice on Thursday afternoon, but had a medical problem believed to be "somehow related to her pregnancy," said Judge Gary Picetti of Alameda County Superior Court. If she is cleared by doctors, she will appear in court today, the judge said.

Esteban is accused of killing her former high school friend Michelle Le, 26, whose body hasn't been found.

Esteban has said that she hated Le and blamed her for ruining her relationship with her former boyfriend, who is the father of her 5-year-old daughter. But she denied any involvement with Le's disappearance.

In court documents released Thursday, police said they had circumstantial evidence showing that Le was dead and that Esteban had killed her.

Le was last seen around 7 p.m. May 27 when she went to her car during a break in a clinical lesson at Kaiser Permanente Medical Center on Hesperian Boulevard in Hayward. Police believe that Esteban, Le's former classmate at Mount Carmel High School in San Diego, killed her in the hospital's parking garage.

Esteban was arrested without incident Wednesday morning at her condominium on Monterra Terrace.

Le's blood was found in Le's 2010 Honda CRV, which she had parked in the Kaiser hospital's parking garage, Hayward police Inspector Fraser Ritchie wrote in a statement outlining the grounds for Esteban's arrest. The day after Le was last seen, her car was discovered a half mile from the garage.

Le's DNA was also found on the bottom of one of Esteban's shoes, Ritchie wrote. Security camera footage placed Esteban at the parking garage before and after Le disappeared, and physical evidence confirmed that Esteban was in Le's Honda, authorities said.

Cell phone records show that both women's phones "traveled on a similar path" from the Kaiser hospital to the Niles and Sunol Canyon areas in Alameda County immediately after Le disappeared, the affidavit said.

Evidence also supports the belief that Le is dead, including publicity over her disappearance and the fact that her financial records and social networking sites "have shown no activity for the victim since her suspicious disappearance," Ritchie wrote.