he police yesterday identified a body found floating in the East River on Tuesday afternoon as that of a Russian woman who vanished two months ago while walking her dog on the Upper East Side. An autopsy found that she had drowned after suffering small bruises on both shins, the authorities said.

But the case remains a mystery. The city's chief medical examiner and the police have not concluded whether the woman, Svetlana Aronov, 44, was murdered, committed suicide or died as a result of an accident. And detectives said they were unsure where and how Ms. Aronov, who left her apartment March 3 with nothing but a house key, a cellphone and her father's 1-year-old cocker spaniel, Bim, ended up in the river.

"We're not in a position of ruling anything out at this point," Police Commissioner Raymond W. Kelly said. "The investigation is obviously going forward vigorously."

Investigators also determined yesterday that a dead dog that washed up late Tuesday near the Throgs Neck Bridge in Queens, several miles from the restaurant in Long Island City where Ms. Aronov's body was found floating under a pier, was not the spaniel, but perhaps a Maltese or a poodle, a police official said. That dog, about 8 years old and weighing 12 pounds, was in the water days to weeks, not weeks to months. There has been no sign of the spaniel.

The bruises on Ms. Aronov's shins, each 15 inches above the soles of her feet, prompted the police to dispatch detectives to measure the railings along the East River promenade near where Ms. Aronov was last seen on the Upper East Side to see if they coincide with the marks on her legs, several investigators said.

Detectives were also seeking to fix the time of her death and were hoping that the silver and gold Cartier watch found on her wrist would provide some clue, investigators said. The watch had stopped at 4:17, according to a senior police official, and an investigator said that detectives were talking to technicians at Cartier and doing tests to determine whether the watch could keep running after it was submerged, and if so, for how long.

Ms. Aronov's badly decomposed body was identified through dental records. Investigators said she was wearing tan slacks, a top and one zipper fur winter boot — the clothes she had on when she vanished.

The police have long feared that Ms. Aronov, who was set to pick her father up at the airport on the afternoon she disappeared, met with foul play. Several investigators had said there was no information to indicate that she had vanished voluntarily, and she did not appear to have mental problems. Her husband, Alexander Aronov, 45, a hematologist who like his wife grew up in St. Petersburg, Russia, has come under some scrutiny.

Homicide detectives always look first to the husband or wife when someone disappears, but investigators did not initially focus on Dr. Aronov as a suspect. As the case has dragged on, however, detectives have focused more attention on the doctor, who has offices in Manhattan and Brooklyn, where he was when his wife disappeared. But he has denied wrongdoing and, according to a Web site created in Ms. Aronov's honor, passed two lie detector tests.

At the same time, investigators have also begun to focus on the possibility that Ms. Aronov may have been depressed. While several have dismissed the notion that someone would take his or her own life with a pet along, others have noted that it is not uncommon for people to kill themselves in the presence of family.

The couple have two daughters, Polina, 22, and Veronica, 9. Ms. Aronov helped her husband with the books and had her own business, dealing part time in Russian books.

Ms. Aronov was last seen at 68th Street and York Avenue. Bloodhounds had traced the spaniel's scent for the four blocks from her family's apartment building between East 63rd and East 64th Streets.

The nearest access to the river is at East 63rd Street, where a footbridge just east of York Avenue spans the Franklin D. Roosevelt Drive. The bridge connects the streets to a walking path, which is separated from the water's edge by a wrought-iron fence.

Ed Hayes, a lawyer for Dr. Aronov, said yesterday that the family was eager to find out what happened to Ms. Aronov. "The only thing I would say is we still don't know what happened and we're trying to figure it out," he said. "It may be that it was just a horrible accident, but right now nobody knows."