UPDATE: The search for Michelle Le has now turned into a homicide investigation.
Police said compelling evidence recovered during the investigation "points conclusively to homicide" and the search has become "an effort of recovery."
"We realize this is the worst possible news for Michelle's family and friends, and for everyone involved in looking for her," police said in a statement Monday night.
In a report on KTVU Tuesday morning, police planned to begin searching rural areas of the East Bay for her body.
Police believe Le was killed based on forensic evidence collected from Le's car and from the Kaiser hospital parking structure where it was parked; information collected during interviews; examination of evidence gathered via search warrants; review of video footage from the garage and other locations; and examination of Le's cellphone records, police said.
As of Monday, more than 25 people have been questioned regarding the case, police said. No one has been charged with Le's murder.
On Monday evening, Hayward police searched the Union City apartment of a woman who was previously questioned as a "person of interest" in the case. The department did not release any other information on the search.
Le was last seen on May 27 at 7 p.m. at Kaiser Permanente Hayward Medical Center's facility at 27303 Sleepy Hollow Ave., Hayward.
She was supposed to meet a friend and drive to Reno after finishing her rotation at the medical facility. She left during a break and did not return, according to Hayward police.
According to media reports, police believe Le was killed in the hospital parking garage by someone who is "not a stranger."
The Alameda County District Attorney's Office is also evaluating the case.
The person of interest, whom Patch is not identifying because she has not been arrested, lives in the Monte Vista apartments off Alvarado Niles Road. She is a former friend of Le's who had been quoted as saying she "hated" Le. The woman was initially questioned last week.
Residents at the Monte Vista apartments said they have not seen the woman since last Monday, May 30, when she knocked on doors, apologizing for the police presence the previous weekend. Police initially detained the woman for questioning on May 28, according to witnesses.
A neighbor, who wished to remain anonymous, said the woman who was questioned was upset because she felt she was being targeted by media. She told the neighbor then that she would be relocating. Neighbors said she had only been living at the apartments for about two months and they didn't see her often.
The news of the case being a homicide came shortly after the reward for information about Le was upped to $65,000, thanks to pledges from the university where she was a nursing program and her workplace, Turner Construction Company, where Le has worked part-time as an accounting clerk for five years, said Samuel Merritt University spokeswoman Elizabeth Valente.
Also in the news Monday was the discovery of a woman's body inside a plastic bag in a Sunnyvale neighborhood. A representative with the Santa Clara County Coroner's Office said there was no information available for release regarding the body that was found.
Hayward police spoke with Sunnyvale officials to see if the body had been identified as an Asian female, but it's believed to be that of a Hispanic adult female, so it's not believed to be connected to the Le case.
On Friday night, at least 200 friends, family members and other supporters , in the neighborhood where Le's car was found, to hold a rally in the search for her.
Bay City News contributed to this report.