A woman was tied to a vehicle with a rope and dragged through suburban streets in a gruesome crime that left a trail of blood more than a mile long, police said.

Neighbors discovered the woman's body before dawn Monday about 20 miles south of Denver. On Tuesday, sheriff's deputies were still trying to learn her identity.

The victim's face was unrecognizable and an orange tow rope was found around her neck, said Nancy Foley, who lives next door to the house where the body was found.

"I was trying to sleep last night, thinking about how this poor lady was dragged, treated worse than an animal," Foley said. "She was really mangled."

Preliminary autopsy results indicated the woman died of asphyxiation and head injuries from being strangled while dragged by a vehicle, sheriff's spokeswoman Kim Castellano said. Toxicology results could take three weeks.

Castellano said investigators Tuesday detained several witnesses for questioning. No one had been arrested or identified as a possible suspect, she said.

A photo of an unidentified couple was found nearby, but investigators did not know whether it was connected to the death, Castellano said.

Investigators were checking missing-person reports for clues.

Authorities stepped up patrols in the once-quiet neighborhood, and residents were locking their doors at night, Foley said.

"It's a very safe neighborhood, or it has been, anyway," she said.

The blood was cleaned off the paved road, but traces remained, upsetting neighbors.

"We don't want to attract any more attention than what we're already getting. This is our little piece of heaven," Foley said.