Police say they may already have interviewed a suspect in the gunpoint abduction of 14-year-old Elizabeth Smart, and they issued this stern warning to the kidnapper on Tuesday:

"To the person that has taken her," Police Chief Rick Dinse said, "understand this:

"We will get you. We will get you. If you have her, you had better release her right now."

Dinse told reporters in a briefing that "we believe that it is possible that we have already talked to or will soon talk to the suspect that is responsible for this crime."

He added, "We do not have a name pegged to that person," but he said the investigation was headed toward focusing on someone who had access to the neighborhood or the house, although not necessarily a family member.

He said the police have received some promising leads in the case.

"We don't have an identified suspect but we do have some analysis of what this suspect is like," Dinse said, adding that police believe the kidnapper is still in the Salt Lake City area.

Police have described the abductor as about 5-foot-8, white, with dark hair, and dressed in a tan denim-type jacket and white baseball cap.

As to whether Elizabeth knew her abductor, Dinse said, "That is a possibility, and I'm not going to comment beyond that."

Dinse told Fox News that Elizabeth's family are "hoping for miracles, [but] I'm hoping it's less than a miracle to get her back alive.

"Obviously, the further we get from the day of her disappearance, the more concerned we get."

Investigators spent several hours in the Smart home early Tuesday morning, searching for clues to the girl's apparent kidnapping at gunpoint a week ago.

The Salt Lake City Police detectives left the sprawling million-dollar home in the Federal Heights neighborhood at 3 a.m., said spokesman Fred Louis. They wanted to be in the home at the same time Elizabeth was kidnapped, between 1 a.m. and 2 a.m., he said.

He would not elaborate on what kinds of forensic tests were done.

"The things we have found so far in the searches have not been of great evidentiary value," Dinse told Fox News.

"We go back into crime scenes all the time. This is not an uncommon procedure."

Seven days after Elizabeth was abducted from the bedroom she shares with her sister, police said they have ruled out the possibility that the girl staged her own abduction and was a runaway. They would only say they based that conclusion on interviews and evidence.

"While we have not located Elizabeth or identified a clear suspect, we have made progress," Dinse said. Police have received 6,000 leads, of which 600 were worthy of following up. Half of the 600 leads have been cleared.

Ed Smart, Elizabeth's father, submitted to a polygraph test on Sunday. The test is being evaluated by the FBI.

"It's just one of the tools we've been using to further the investigation," police Capt. Scott Atkinson said. "We're looking at every possible angle."

Police would not say what questions were asked, and a family spokesman did not know whether Smart had an attorney present during the questioning. Police did say other family members may be tested.

In a statement released Monday evening, Smart said, "When asked by law enforcement I fully cooperated because I have nothing to hide. We are doing everything in our power to bring back Elizabeth."

Police have re-interviewed 9-year-old Mary Katherine Smart, who told investigators that a gunman came into the bedroom she shared with her older sister and forced Elizabeth to go with him. She said he told her that her sister would be hurt if she told anyone. Police said it was at least two hours before she woke her parents and told them.

"Her story was consistent and we did learn some things about the suspect we didn't know before," Dinse said.

Dinse said police are staying with the child's initial description of the suspect.

"The description that we have is what we want to go with," Dinse said. "We've given all the description out that we think is helpful at this point."

Atkinson said FBI agents and 60 police investigators continued to sift through the thousands of tips, but, "At this point, we're no closer to solving her disappearance."

The volunteer search through the city and mountain foothills was tapering off. On the first day of the search, 1,200 people volunteered to find Elizabeth. By Tuesday morning that number had dwindled to 200.

However, the search also is expanding into other areas.

Tom Smart, one of Elizabeth's uncles, asked for 40 or 50 all-terrain vehicle owners to help search the West Desert area.

Chris Thomas, a spokesman for the family, said 55 ATV owners turned out, each searching a 25 square mile area.

He said the ATV search would be continued Tuesday and there also were discussions about holding a four-wheel-drive search in the mountains and enrolling horse posses.

Fox News' Alicia Acuna and the Associated Press contributed to this report.