An autopsy provided few additional details, according to Pleasanton police Lt. Jeff Bretzing.
"Unfortunately the results of the autopsy are inconclusive. We are unable to make an absolute identification of the body. Attempts to determine the identity through fingerprints have been unsuccessful," Bretzing said. "We are do know it's the body of a female, most likely an adult. The coroner couldn't determine the exact age or ethnicity."
Bretzing said the woman had dark-colored hair, but said the condition of the body made it impossible to say the exact color. The woman was clothed in pajama bottoms and an Old Navy shirt -- Bretzing would not comment on the style or color of the woman's clothing -- and wore blue fingernail polish.
"The cause of death is unknown. The time of death is unknown," he said. "There has been some decomposition, so some time has gone by. The coroner's office will determine that."
He said it's unlikely the body is that of Sierra Lamar, a 15-year-old cheerleader from Morgan Hill, who's been missing for two months and is believed to be dead. Bretzing said Pleasanton police have been in touch with many other police departments in the Bay Area in an attempt to match a missing persons case to the discovery.
The woman's body was found in the trash can May 24 along the side of Dublin Canyon Road in Pleasanton.
Police received a call at about 11:30 a.m. after someone spotted the plastic trash can on the side of Dublin Canyon Road, not far from its intersection with Laurel Creek Drive, Bretzing said.
"Officers discovered inside the can what appear to be human remains," Bretzing said, adding the can was in foliage adjacent to the road. "We don't know how long it's been there."
The territory is nominally the jurisdiction of the Alameda County Sheriff's Office, but Bretzing said Pleasanton police will remain the lead agency in the investigation.
"Nothing like this has ever happened here before," he said of the discovery.
Bretzing confirm that police are still awaiting lab results in an earlier case.
On May 7, a mother and daughter, 37-year-old Amy Freeman Burton and 13-year-old Ainsley Freeman, were found with fatal wounds at their home in the 3200 block of Stacey Court.
Preliminary results indicate that Ainsley Freeman did not shoot herself. The coroner's report said it was "unclear" whether 37-year-old Amy Freeman Burton's wound was self inflicted, adding, "That is not being ruled out."
Bullets recovered from both victims are consistent with those found in the handgun that was located near the two, one of two unregistered pistols found in a search of the home.