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.
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 was completed, but the cause of death is deferred pending further examination, assistant chief coroner Ed Winter said Thursday. That may take six to eight weeks.
It will be several weeks before investigators have the toxicology lab report which would show whether Lam had any drugs in her system.
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. 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. Clad in a red hoodie, Lam at one point walks out of the elevator before returning to it, pushing the buttons again. She then stands outside the open elevator doorway, motioning with her hands, before apparently walking away.
Lam checked into the Cecil Hotel five days earlier, January 26, on her way to Santa Cruz, California, according to police in her hometown of Vancouver, British Columbia.
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.
Randy Schmidt, a spokesman for the University of British Columbia, said Lam was registered in a class in August, but was not registered in any classes this year, according to records.
"Unfortunately, we do not have much more to say, other than to extend our deepest sympathies to the family," said Schmidt.