LOS ANGELES (CNN) -- Two days after the grisly discovery, the case of the Los Angeles hotel water tank corpse is a mystery with many unanswered questions.
The decomposing body of Elisa Lam floated inside a water tank on the roof of the Cecil Hotel while guests brushed their teeth, bathed and drank with water from it for as long as 19 days.
A maintenance worker, checking on complaints about the hotel's water, found the 21-year-old Canadian tourist inside one of four water cisterns Tuesday morning, Los Angeles Police Sgt. Rudy Lopez said.
How and where did Elisa Lam die?
Los Angeles robbery-homicide detectives are treating this as a suspicious death for obvious reasons, Lopez said. Falling into a covered water tank behind a locked door on top of a roof would be an unusual accident.
An autopsy being conducted Thursday afternoon by the Los Angeles County coroner will look for clues.
Any marks, injuries or wounds may suggest Lam died elsewhere and was dumped into the tank by her killer.
Water in Lam's lungs could be a sign that she drowned, but it might not tell why she was inside the small tank.
Preliminary results may be announced late Thursday or Friday morning, according to assistant chief coroner Ed Winter. It will be several weeks before investigators have the toxicology lab report which would show whether Lam had any drugs in her system.
One clue comes from security camera video of Lam inside a hotel elevator the last day she was seen. She is seen walking into the elevator, pushing the buttons for four floors and then peering out of the opened elevator door as if she is hiding or looking for someone.
Lam checked into the Cecil Hotel five days earlier, January 26, on her way to Santa Cruz, California, according to police in her home town of Vancouver, British Columbia.
Why did it it take so long to find Lam?
Lam's parents reported the University of British Columbia student missing in early February. Her daily calls home stopped on January 31, police told reporters on February 6 at a Los Angeles news conference.
Because it was an international case -- and her parents and sister flew to California to find answers -- the case may have gotten more attention than most of the several thousand missing person reports made in Los Angeles each year.
A search of the hotel then found no sign of Lam, including a trip to the roof with a police search dog, Lopez said.
Strange things began happening with the hotel's water supply later in the month, according to Sabina and Michael Baugh, a British couple who spent eight days there until checking out Wednesday. The water pressure dropped to a trickle at times.
"The shower was awful," Sabina Baugh said. "When you turned the tap on, the water was coming black first for two seconds and then it was going back to normal."
The tap water "tasted horrible," Baugh said. "It had a very funny, sweety, disgusting taste. It's a very strange taste. I can barely describe it."
But for a week, they never complained. "We never thought anything of it," she said. "We thought it was just the way it was here."
Knowing now what they didn't know then about the water is sickening, Michael Baugh said. "It makes you feel literally physically sick, but more than that you feel it psychologically. You think about it and it's not good."
Eventually, the hotel maintenance department investigated the water problem, sending a worker to look into the tank, police said. He saw Lam's lifeless body at the bottom.
Why did hotel stay open after discovery?
New guests continued to check into the Cecil in the hours after firefighters removed Lam's body from the water tank. But each guest was asked to sign a waiver releasing the hotel from liability if they become ill. "You do so at your own risk and peril," the hotel's release said. Guests who already paid for their rooms would not get refunds if they move out, it said.
CNN's repeated calls to the hotel for comment were unreturned Wednesday and Thursday.
The Los Angeles Public Health Department immediately tested the water supply, but told the manager they could stay open as long as they provided bottle water and warned guests not to drink the tap water, spokesman Alan Solomon said.
Results of the testing to see whether the water posed a health risk could be available later Thursday, Solomon said.
Several guests interviewed by CNN on Wednesday indicated the hotel management did not tell them about the body in the water supply they had been drinking and bathing in.
Qui Nguyen learned about it from a CNN reporter Wednesday morning. He decided not to sign the waiver and instead find a new hotel.
Many of its guests are tourists from other countries drawn by the hotel's billing as a "European-style" hotel that is the perfect accommodation for "spend-thrifty travelers."
But if they take Kim Cooper's tour bus ride through the neighborhood, they would hear about the Cecil being the former temporary home to at least two convicted murderers, including "Night Stalker" serial killer Richard Ramirez. Ramirez paid $14 a day to stay on the 14th floor during his 1980s killing spree, Cooper said.
The Cecil Hotel is "in the heart of the action, allowing our guest to embrace the city and the surrounding areas that make Los Angeles famous," according to the description you'll hear when you call there and are placed on hold.
In fact, the hotel is just a few blocks away from the infamous Skid Row district in downtown Los Angeles, but 16 miles from the beaches of Santa Monica, eight miles from Hollywood's Walk of Fame and 12 miles from glamorous streets of Beverly Hills that are prominently featured on the Cecil's website.
If you want a reservation at the Cecil you will have to wait until next month. The website said the hotel is "sold out" until March 1. After then, you can book a room for $65.